Posted on by Lawrence Tabak, D.D.S., Ph.D.
Happy New Year! I hope everyone finished 2022 with plenty to celebrate, whether it was completing a degree or certification, earning a promotion, attaining a physical fitness goal, or publishing a hard-fought scientific discovery.
If the latter, you are in good company. Last year produced some dazzling discoveries, and the news and editorial staff at the journal Science kept a watchful eye on the most high-impact advances of 2022. In December, the journal released its list of the top 10 advances across the sciences, from astronomy to zoology. In case you missed it, Science selected NASA’s James Webb Space Telescope (JWST) as the 2022 Breakthrough of the Year .
This unique space telescope took 20 years to complete, but it has turned out to be time well spent. Positioned 1.5-million-kilometers from Earth, the JWST and its unprecedented high-resolution images of space have unveiled the universe anew for astronomers and wowed millions across the globe checking in online. The telescope’s image stream, beyond its sheer beauty, will advance study of the early Universe, allowing astronomers to discover distant galaxies, explore the early formation of stars, and investigate the possibility of life on other planets.
While the biomedical sciences didn’t take home the top prize, they were well represented among Science’s runner-up breakthroughs. Some of these biomedical top contenders also have benefited, directly or indirectly, from NIH efforts and support. Let’s take a look:
RSV vaccines nearing the finish line: It’s been one of those challenging research marathons. But scientists last year started down the homestretch with the first safe-and-effective vaccine for respiratory syncytial virus (RSV), a leading cause of severe respiratory illness in the very young and the old.
In August, the company Pfizer presented evidence that its experimental RSV vaccine candidate offered protection for those age 60 and up. Later, they showed that the same vaccine, when administered to pregnant women, helped to protect their infants against RSV for six months after birth. Meanwhile, in October, the company GSK announced encouraging results from its late-stage phase III trial of an RSV vaccine in older adults.
As Science noted, the latest clinical progress also shows the power of basic science. For example, researchers have been working with chemically inactivated versions of the virus to develop the vaccine. But these versions have a key viral surface protein that changes its shape after fusing with a cell to start an infection. In this configuration, the protein elicits only weak levels of needed protective antibodies.
Back in 2013, Barney Graham, then with NIH’s National Institute of Allergy and Infectious Diseases (NIAID), and colleagues, solved the problem . Graham’s NIH team discovered a way to lock the protein into its original prefusion state, which the immune system can better detect. This triggers higher levels of potent antibodies, and the discovery kept the science—and the marathon—moving forward.
These latest clinical advances come as RSV and other respiratory viruses, including SARS-CoV-2, the cause of COVID-19, are sending an alarming number of young children to the hospital. The hope is that researchers will cross the finish line this year or next, and we’ll have the first approved RSV vaccine.
Virus fingered as cause of multiple sclerosis: Researchers have long thought that multiple sclerosis, or MS, has a viral cause. Pointing to the right virus with the required high degree of certainty has been the challenge, slowing progress on the treatment front for those in need. As published in Science last January, Alberto Ascherio, Harvard T.H. Chan School of Public Health, Boston, and colleagues produced the strongest evidence yet that MS is caused by the Epstein-Barr virus (EBV), a herpesvirus also known for causing infectious mononucleosis .
The link between EBV and MS had long been suspected. But it was difficult to confirm because EBV infections are so widespread, and MS is so disproportionately rare. In the recent study, the NIH-supported researchers collected blood samples every other year from more than 10 million young adults in the U.S. military, including nearly 1,000 who were diagnosed with MS during their service. The evidence showed that the risk of an MS diagnosis increased 32-fold after EBV infection, but it held steady following infection with any other virus. Levels in blood serum of a biomarker for MS neurodegeneration also went up only after an EBV infection, suggesting that the viral illness is a leading cause for MS.
Further evidence came last year from a discovery published in the journal Nature by William Robinson, Stanford University School of Medicine, Stanford, CA, and colleagues. The NIH-supported team found a close resemblance between an EBV protein and one made in the healthy brain and spinal cord . The findings suggest an EBV infection may produce antibodies that mistakenly attack the protective sheath surrounding our nerve cells. Indeed, the study showed that up to one in four people with MS had antibodies that bind both proteins.
This groundbreaking research suggests that an EBV vaccine and/or antiviral drugs that thwart this infection might ultimately prevent or perhaps even cure MS. Of note, NIAID launched last May an early-stage clinical trial for an experimental EBV vaccine at the NIH Clinical Center, Bethesda, MD.
AI Gets Creative: Science’s 2021 Breakthrough of the Year was AI-powered predictions of protein structure. In 2022, AI returned to take another well-deserved bow. This time, Science singled out AI’s now rapidly accelerating entry into once uniquely human attributes, such as artistic expression and scientific discovery.
On the scientific discovery side, Science singled out AI’s continued progress in getting creative with the design of novel proteins for vaccines and myriad other uses. One technique, called “hallucination,” generates new proteins from scratch. Researchers input random amino acid sequences into the computer, and it randomly and continuously mutates them into sequences that other AI tools are confident will fold into stable proteins. This greatly simplifies the process of protein design and frees researchers to focus their efforts on creating a protein with a desired function.
AI research now engages scientists around world, including hundreds of NIH grantees. Taking a broader view of AI, NIH recently launched the Artificial Intelligence/Machine Learning Consortium to Advance Health Equity and Researcher Diversity (AIM-AHEAD) Program. It will help to create greater diversity within the field, which is a must. A lack of diversity could perpetuate harmful biases in how AI is used, how algorithms are developed and trained, and how findings are interpreted to avoid health disparities and inequities for underrepresented communities.
And there you have it, some of the 2022 breakthroughs from Science‘s news and editorial staff. Of course, the highlighted biomedical breakthroughs don’t capture the full picture of research progress. There were many other milestone papers published in 2022 that researchers worldwide will build upon in the months and years ahead to make further progress in their disciplines and, for some, draw the attention of Science’s news and editorial staff. Here’s to another productive year in biomedical research, which the blog will continue to feature and share with you as it unfolds in 2023.
 2022 Breakthrough of the Year. Science. Dec 15, 2022.
 Structure of RSV fusion glycoprotein trimer bound to a prefusion-specific neutralizing antibody. McLellan JS, Chen M, Leung S, Kwong PD, Graham BS, et al. Science. 2013 May 31;340(6136):1113-1117.
 Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis. Bjornevik K, Cortese M, Healy BC, Kuhle J, Mina MJ, Leng Y, Elledge SJ, Niebuhr DW, Scher AI, Munger KL, Ascherio A. Science. 2022 Jan 21;375(6578):296-301.
 Clonally expanded B cells in multiple sclerosis bind EBV EBNA1 and GlialCAM. Lanz TV, Brewer RC, Steinman L, Robinson WH, et al. Nature. 2022 Mar;603(7900):321-327.
Respiratory Syncytial Virus (RSV) (National Institute of Allergy and Infectious Diseases/NIH)
Multiple Sclerosis (National Institute of Neurological Disorders and Stroke/NIH)
Barney Graham (Morehouse School of Medicine, Atlanta)
Alberto Ascherio (Harvard T.H. Chan School of Public Health, Boston)
Robinson Lab (Stanford Medicine, Stanford, CA)
James Webb Space Telescope (Goddard Space Flight Center/NASA, Greenbelt, MD)
Posted on by Lawrence Tabak, D.D.S., Ph.D.
More than 215 million people in the United States are now fully vaccinated against the SARS-CoV-2 virus responsible for COVID-19 . More than 40 percent—more than 94 million people—also have rolled up their sleeves for an additional, booster dose. Now, an NIH-funded study exploring how mRNA vaccines are performing over time comes as a reminder of just how important it will be to keep those COVID-19 vaccines up to date as coronavirus variants continue to circulate.
The results, published in the journal Science Translational Medicine, show that people who received two doses of either the Pfizer or Moderna COVID-19 mRNA vaccines did generate needed virus-neutralizing antibodies . But levels of those antibodies dropped considerably after six months, suggesting declining immunity over time.
The data also reveal that study participants had much reduced protection against newer SARS-CoV-2 variants, including Delta and Omicron. While antibody protection remained stronger in people who’d also had a breakthrough infection, even that didn’t appear to offer much protection against infection by the Omicron variant.
The new study comes from a team led by Shan-Lu Liu at The Ohio State University, Columbus. They wanted to explore how well vaccine-acquired immune protection holds up over time, especially in light of newly arising SARS-CoV-2 variants.
This is an important issue going forward because mRNA vaccines train the immune system to produce antibodies against the spike proteins that crown the surface of the SARS-CoV-2 coronavirus. These new variants often have mutated, or slightly changed, spike proteins compared to the original one the immune system has been trained to detect, potentially dampening the immune response.
In the study, the team collected serum samples from 48 fully vaccinated health care workers at four key time points: 1) before vaccination, 2) three weeks after the first dose, 3) one month after the second dose, and 4) six months after the second dose.
They then tested the ability of antibodies in those samples to neutralize spike proteins as a correlate for how well a vaccine works to prevent infection. The spike proteins represented five major SARS-CoV-2 variants. The variants included D614G, which arose very soon after the coronavirus first was identified in Wuhan and quickly took over, as well as Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529).
The researchers explored in the lab how neutralizing antibodies within those serum samples reacted to SARS-CoV-2 pseudoviruses representing each of the five variants. SARS-CoV-2 pseudoviruses are harmless viruses engineered, in this case, to bear coronavirus spike proteins on their surfaces. Because they don’t replicate, they are safe to study without specially designed biosafety facilities.
At any of the four time points, antibodies showed a minimal ability to neutralize the Omicron spike protein, which harbors about 30 mutations. These findings are consistent with an earlier study showing a significant decline in neutralizing antibodies against Omicron in people who’ve received the initial series of two shots, with improved neutralizing ability following an additional booster dose.
The neutralizing ability of antibodies against all other spike variants showed a dramatic decline from 1 to 6 months after the second dose. While there was a marked decline over time after both vaccines, samples from health care workers who’d received the Moderna vaccine showed about twice the neutralizing ability of those who’d received the Pfizer vaccine. The data also suggests greater immune protection in fully vaccinated healthcare workers who’d had a breakthrough infection with SARS-CoV-2.
In addition to recommending full vaccination for all eligible individuals, the Centers for Disease Control and Prevention (CDC) now recommends everyone 12 years and up should get a booster dose of either the Pfizer or Moderna vaccines at least five months after completing the primary series of two shots . Those who’ve received the Johnson & Johnson vaccine should get a booster at least two months after receiving the initial dose.
While plenty of questions about the durability of COVID-19 immunity over time remain, it’s clear that the rapid deployment of multiple vaccines over the course of this pandemic already has saved many lives and kept many more people out of the hospital. As the Omicron threat subsides and we start to look forward to better days ahead, it will remain critical for researchers and policymakers to continually evaluate and revise vaccination strategies and recommendations, to keep our defenses up as this virus continues to evolve.
 COVID-19 vaccinations in the United States. Centers for Disease Control and Prevention. February 27, 2022.
 Neutralizing antibody responses elicited by SARS-CoV-2 mRNA vaccination wane over time and are boosted by breakthrough infection. Evans JP, Zeng C, Carlin C, Lozanski G, Saif LJ, Oltz EM, Gumina RJ, Liu SL. Sci Transl Med. 2022 Feb 15:eabn8057.
 COVID-19 vaccine booster shots. Centers for Disease Control and Prevention. Feb 2, 2022.
COVID-19 Research (NIH)
Shan-Lu Liu (The Ohio State University, Columbus)
NIH Support: National Institute of Allergy and Infectious Diseases; National Cancer Institute; National Heart, Lung, and Blood Institute; Eunice Kennedy Shriver National Institute of Child Health and Human Development
Posted on by Dr. Francis Collins
There’s been great concern about the new Omicron variant of SARS-CoV-2, the coronavirus that causes COVID-19. A major reason is Omicron has accumulated over 50 mutations, including about 30 in the spike protein, the part of the coronavirus that mRNA vaccines teach our immune systems to attack. All of these genetic changes raise the possibility that Omicron could cause breakthrough infections in people who’ve already received a Pfizer or Moderna mRNA vaccine.
So, what does the science show? The first data to emerge present somewhat encouraging results. While our existing mRNA vaccines still offer some protection against Omicron, there appears to be a significant decline in neutralizing antibodies against this variant in people who have received two shots of an mRNA vaccine.
However, initial results of studies conducted both in the lab and in the real world show that people who get a booster shot, or third dose of vaccine, may be better protected. Though these data are preliminary, they suggest that getting a booster will help protect people already vaccinated from breakthrough or possible severe infections with Omicron during the winter months.
Though Omicron was discovered in South Africa only last month, researchers have been working around the clock to learn more about this variant. Last week brought the first wave of scientific data on Omicron, including interesting work from a research team led by Alex Sigal, Africa Health Research Institute, Durban, South Africa .
In lab studies working with live Omicron virus, the researchers showed that this variant still relies on the ACE2 receptor to infect human lung cells. That’s really good news. It means that the therapeutic tools already developed, including vaccines, should generally remain useful for combatting this new variant.
Sigal and colleagues also tested the ability of antibodies in the plasma from 12 fully vaccinated individuals to neutralize Omicron. Six of the individuals had no history of COVID-19. The other six had been infected with the original variant in the first wave of infections in South Africa.
As expected, the samples showed very strong neutralization against the original SARS-CoV-2 variant. However, antibodies from people who’d been previously vaccinated with the two-dose Pfizer vaccine took a significant hit against Omicron, showing about a 40-fold decline in neutralizing ability.
This escape from immunity wasn’t complete. Indeed, blood samples from five individuals showed relatively good antibody levels against Omicron. All five had previously been infected with SARS-CoV-2 in addition to being vaccinated. These findings add to evidence on the value of full vaccination for protecting against reinfections in people who’ve had COVID-19 previously.
Also of great interest were the first results of the Pfizer study, which the company made available in a news release . Pfizer researchers also conducted laboratory studies to test the neutralizing ability of blood samples from 19 individuals one month after a second shot compared to 20 others one month after a booster shot.
These studies showed that the neutralizing ability of samples from those who’d received two shots had a more than 25-fold decline relative to the original virus. Together with the South Africa data, it suggests that the two-dose series may not be enough to protect against breakthrough infections with the Omicron variant.
In much more encouraging news, their studies went on to show that a booster dose of the Pfizer vaccine raised antibody levels against Omicron to a level comparable to the two-dose regimen against the original variant (as shown in the figure above). While efforts already are underway to develop an Omicron-specific COVID-19 vaccine, these findings suggest that it’s already possible to get good protection against this new variant by getting a booster shot.
Very recently, real-world data from the United Kingdom, where Omicron cases are rising rapidly, are providing additional evidence for how boosters can help. In a preprint , Andrews et. al showed the effectiveness of two shots of Pfizer mRNA vaccine trended down after four months to about 40 percent. That’s not great, but note that 40 percent is far better than zero. So, clearly there is some protection provided.
Most impressively (as shown in the figure from Andrews N, et al.) a booster substantially raised that vaccine effectiveness to about 80 percent. That’s not quite as high as for Delta, but certainly an encouraging result. Once again, these data show that boosting the immune system after a pause produces enhanced immunity against new viral variants, even though the booster was designed from the original virus. Your immune system is awfully clever. You get both quantitative and qualitative benefits.
It’s also worth noting that the Omicron variant mostly doesn’t have mutations in portions of its genome that are the targets of other aspects of vaccine-induced immunity, including T cells. These cells are part of the body’s second line of defense and are generally harder for viruses to escape. While T cells can’t prevent infection, they help protect against more severe illness and death.
It’s important to note that scientists around the world are also closely monitoring Omicron’s severity While this variant appears to be highly transmissible, and it is still early for rigorous conclusions, the initial research indicates this variant may actually produce milder illness than Delta, which is currently the dominant strain in the United States.
But there’s still a tremendous amount of research to be done that could change how we view Omicron. This research will take time and patience.
What won’t change, though, is that vaccines are the best way to protect yourself and others against COVID-19. (And these recent data provide an even-stronger reason to get a booster now if you are eligible.) Wearing a mask, especially in public indoor settings, offers good protection against the spread of all SARS-CoV-2 variants. If you’ve got symptoms or think you may have been exposed, get tested and stay home if you get a positive result. As we await more answers, it’s as important as ever to use all the tools available to keep yourself, your loved ones, and your community happy and healthy this holiday season.
 SARS-CoV-2 Omicron has extensive but incomplete escape of Pfizer BNT162b2 elicited neutralization and requires ACE2 for infection. Sandile C, et al. Sandile C, et al. medRxiv preprint. December 9, 2021.
 Pfizer and BioNTech provide update on Omicron variant. Pfizer. December 8, 2021.
 Effectiveness of COVID-19 vaccines against the Omicron (B.1.1.529) variant of concern. Andrews N, et al. KHub.net preprint. December 10, 2021.
COVID-19 Research (NIH)
Sigal Lab (Africa Health Research Institute, Durban, South Africa)
Posted on by Dr. Francis Collins
The winter holidays are approaching, and among the many things to be grateful for this year is that nearly 200 million Americans are fully vaccinated for COVID-19. That will make it safer to spend time with friends and family, though everyone should remain vigilant just to be on the safe side. Though relatively uncommon, breakthrough infections are possible. That’s why the Centers for Disease Control and Prevention (CDC) recommends booster shots for several at-risk groups, including folks 65 years and older, those with underlying medical conditions, and people whose occupations place them at high risk of exposure.
One of the main studies providing the evidence for CDC’s recommendation was recently published in the New England Journal of Medicine . It found that vaccine-induced immunity, while still quite protective against infection and severe illness from COVID-19, can wane after several months.
The study is yet another highly informative report from Israel, where public health officials launched a particularly vigorous national vaccination campaign in December 2020. More than half of adult Israelis received two doses of the Pfizer vaccine within the first three months of the campaign. By May 2021, Israel had extremely small numbers of confirmed COVID-19 cases—just a few dozen per day.
But the numbers crept back up in June 2021. The rise also included a substantial number of breakthrough infections in vaccinated individuals. The vast majority of those cases in June—98 percent—were caused by the emerging Delta variant.
Researchers led by Yair Goldberg, Technion-Israel Institute of Technology, Haifa, wondered whether this resurgence of COVID-19 could be fully explained by the rise of the more infectious Delta variant. Or, they wondered, did the waning of immunity over time also play a role?
To find out, the researchers looked to over 4.7 million fully vaccinated Israeli adults, more than 13,000 of whom had breakthrough infections from July 11 to 31, 2021 with SARS-CoV-2. The researchers looked for an association between the rate of confirmed infections and the time that had passed since vaccination. Without any significant waning of immunity, one shouldn’t see any difference in infection rates among people who were fully vaccinated at the earliest opportunity versus those vaccinated later.
The results were clear: the rate of confirmed COVID-19 infection revealed a slow but steady waning of immunity over time. Among individuals 60 years or older who were fully vaccinated last January, the number of confirmed breakthrough infections was 3.3 per 1,000 people during the three weeks of the study. Those who were vaccinated in February and March had lower infection rates of 2.2 per 1,000 and 1.7 per 1,000, respectively. The data revealed a similar pattern in those aged 40 to 59 and those aged 16 to 39.
An important question is whether these breakthrough infections were serious enough to require hospitalization. While such cases were much less common, more than 400 of those with confirmed COVID-19 breakthroughs went on to develop severe illness. And, again, the data show a similar pattern of waning immunity. The rate of severe COVID-19 among adults 60 years of age or older who were fully vaccinated in January was 0.34 cases per 1,000 persons. The rate of severe illness dropped to 0.26 cases per 1,000 among those vaccinated in February and 0.15 cases per 1,000 for those vaccinated in March. The researchers report that the number of severe COVID-19 cases among the younger fully vaccinated groups were too small to draw any conclusions.
While the Delta variant surely has played a role in the resurgence of COVID-19 in recent months, these findings suggest that waning immunity also is an important factor. Understanding these dynamics is essential for making critical policy decisions. In fact, these data were a key factor in the decision by the Israeli Ministry of Health in July 2021 to approve administration of COVID-19 booster shots for individuals who’d been vaccinated at least 5 months before.
Back in the U.S., if you were among those who got your vaccine on the early side—good for you. If it’s been more than six months since your original shots, and if you are in one of the risk groups, you should consider a COVID-19 booster shot to remain optimally protected in the months ahead. I’ll be getting my Moderna booster this week. While you’re at it, consider getting your annual flu shot taken care of, too. The CDC guidelines state that it’s perfectly OK to get your COVID-19 and flu shots at the same time.
 Waning immunity after the BNT162b2 vaccine in Israel. Goldberg Y, Mandel M, Bar-On YM, Bodenheimer O, Freedman L, Haas EJ, Milo R, Alroy-Preis S, Ash N, Huppert A. N Engl J Med. 2021 Oct 27.
COVID-19 Research (NIH)
COVID-19 Vaccine Booster Shots (Centers for Disease Control and Prevention)
Posted on by Dr. Francis Collins
To see how COVID-19 vaccines are working in the real world, Israel has provided particularly compelling data. The fact that Israel is relatively small, keeps comprehensive medical records, and has a high vaccination rate with a single vaccine (Pfizer) has contributed to its robust data collection. Now, a new Israeli study offers some insight into those relatively uncommon breakthrough infections. It confirms that breakthrough cases, as might be expected, arise most often in individuals with lower levels of neutralizing antibodies.
The findings reported in The New England Journal of Medicine focused on nearly 1,500 of about 11,500 fully vaccinated health care workers at Sheba Medical Center, Ramat Gan, Israel . All had received two doses of the Pfizer mRNA vaccine. But, from December 19, 2020 to April 28, 2021, they were tested for a breakthrough infection due to a known exposure to someone with COVID-19 or possible symptoms of the disease.
Just 39 confirmed breakthrough cases were found, indicating a breakthrough infection rate of just 0.4 percent. That’s consistent with rates reported in previous studies. Most in the Israeli study who tested positive for COVID-19 had mild or no symptoms and none required hospitalization.
In the new study, researchers led by Gili Regev-Yochay at Sheba Medical Center’s Infection Control and Prevention Unit, characterized as many breakthrough infections as possible among the health care workers. Almost half of the infections involved members of the hospital nursing staff. But breakthrough cases also were found in hospital administration, maintenance workers, doctors, and other health professionals.
The average age of someone with a breakthrough infection was 42, and it’s notable that only one person was known to have a weakened immune system. The most common symptoms were respiratory congestion, muscle aches (myalgia), and loss of smell or taste. Most didn’t develop a fever. At six weeks after diagnosis, 19 percent reported having symptoms of Long COVID syndrome, including prolonged loss of smell, persistent cough, weakness, and fatigue. About a quarter stayed home from work for longer than the required 10 days, and one had yet to return to work at six weeks.
For 22 of the 39 people with a breakthrough infection, the researchers had results of neutralizing antibody tests from the week leading up to their positive COVID-19 test result. To look for patterns in the antibody data, they matched those individuals to 104 uninfected people for whom they also had antibody test results. These data showed that those with a breakthrough infection had consistently lower levels of neutralizing antibodies circulating in their bloodstream to SARS-CoV-2, the coronavirus that causes COVID-19. In general, higher levels of neutralizing antibodies are associated with greater protection and lower infectivity—though other aspects of the immune system (memory B cells and cell-mediated immunity) also contribute.
Importantly, in all cases for which there were relevant data, the source of the breakthrough infection was thought to be an unvaccinated person. In fact, more than half of those who developed a breakthrough infection appeared to have become infected from an unvaccinated member of their own household.
Other cases were suspected to arise from exposure to an unvaccinated coworker or patient. Contact tracing found no evidence that any of the 39 health care workers with a breakthrough infection passed it on to anyone else.
The findings add to evidence that full vaccination and associated immunity offer good protection against SARS-CoV-2 infection and severe illness. Understanding how SARS-CoV-2 immunity changes over time is key for charting the course of this pandemic and making important decisions about COVID-19 vaccine boosters.
Many questions remain. For instance, it’s not clear from the study whether lower neutralizing antibodies in those with breakthrough cases reflect waning immunity or, for reasons we don’t yet understand, those individuals may have had a more limited immune response to the vaccine. Also, this study was conducted before the Delta variant became dominant in Israel (and now in the whole world).
Overall, these findings provide more reassurance that these vaccines are extremely effective. Breakthrough infections, while they can and do occur, are a relatively uncommon event. Here in the U.S., the Centers for Disease Control and Prevention (CDC) has recently estimated that infection is six times less likely for vaccinated than unvaccinated persons . That those with immunity tend to have mild or no symptoms if they do develop a breakthrough case, however, is a reminder that these cases could easily be missed, and they could put vulnerable populations at greater risk. It’s yet another reason for all those who can to get themselves vaccinated as soon as possible or consider a booster shot when they become eligible.
 Covid-19 breakthrough infections in vaccinated health care workers. Bergwerk M, Gonen T, Lustig Y, Amit S, Lipsitch M, Cohen C, Mandelboim M, Levin EG, Rubin C, Indenbaum V, Tal I, Zavitan M, Zuckerman N, Bar-Chaim A, Kreiss Y, Regev-Yochay G. N Engl J Med. 2021 Oct 14;385(16):1474-1484.
 Rates of COVID-19 cases and deaths by vaccination status, COVID Data Tracker, Centers for Disease and Prevention. Accessed October 25, 2021.
COVID-19 Research (NIH)
Sheba Medical Center (Ramat Gan, Israel)
Posted on by Dr. Francis Collins
Clinical trials have shown the COVID-19 vaccines now being administered around the country are highly effective in protecting fully vaccinated individuals from the coronavirus SARS-CoV-2. But will they continue to offer sufficient protection as the frequency of more transmissible and, in some cases, deadly emerging variants rise?
More study and time is needed to fully answer this question. But new data from Israel offers an early look at how the Pfizer/BioNTech vaccine is holding up in the real world against coronavirus “variants of concern,” including the B.1.1.7 “U.K. variant” and the B.1.351 “South African variant.” And, while there is some evidence of breakthrough infections, the findings overall are encouraging.
Israel was an obvious place to look for answers to breakthrough infections. By last March, more than 80 percent of the country’s vaccine-eligible population had received at least one dose of the Pfizer/BioNTech vaccine. An earlier study in Israel showed that the vaccine offered 94 percent to 96 percent protection against infection across age groups, comparable to the results of clinical trials. But it didn’t dig into any important differences in infection rates with newly emerging variants, post-vaccination.
To dig a little deeper into this possibility, a team led by Adi Stern, Tel Aviv University, and Shay Ben-Shachar, Clalit Research Institute, Tel Aviv, looked for evidence of breakthrough infections in several hundred people who’d had at least one dose of the Pfizer/BioNTech vaccine . The idea was, if this vaccine were less effective in protecting against new variants of concern, the proportion of infections caused by them should be higher in vaccinated compared to unvaccinated individuals.
During the study, reported as a pre-print in MedRxiv, it became clear that B.1.1.7 was the predominant SARS-CoV-2 variant in Israel, with its frequency increasing over time. By comparison, the B.1.351 “South African” variant was rare, accounting for less than 1 percent of cases sampled in the study. No other variants of concern, as defined by the World Health Organization, were detected.
In total, the researchers sequenced SARS-CoV-2 from more than 800 samples, including vaccinated individuals and matched unvaccinated individuals with similar characteristics including age, sex, and geographic location. They identified nearly 250 instances in which an individual became infected with SARS-CoV-2 after receiving their first vaccine dose, meaning that they were only partially protected. Almost 150 got infected sometime after receiving the second dose.
Interestingly, the evidence showed that these breakthrough infections with the B.1.1.7 variant occurred slightly more often in people after the first vaccine dose compared to unvaccinated people. No evidence was found for increased breakthrough rates of B.1.1.7 a week or more after the second dose. In contrast, after the second vaccine dose, infection with the B.1.351 became slightly more frequent. The findings show that people remain susceptible to B.1.1.7 following a single dose of vaccine. They also suggest that the two-dose vaccine may be slightly less effective against B.1.351 compared to the original or B.1.1.7 variants.
It’s important to note, however, that the researchers only observed 11 infections with the B.1.351 variant—eight of them in individuals vaccinated with two doses. Interestingly, all eight tested positive seven to 13 days after receiving their second dose. No one in the study tested positive for this variant two weeks or more after the second dose.
Many questions remain, including whether the vaccines reduced the duration and/or severity of infections. Nevertheless, the findings are a reminder that—while these vaccines offer remarkable protection—they are not foolproof. Breakthrough infections can and do occur.
In fact, in a recent report in the New England Journal of Medicine, NIH-supported researchers detailed the experiences of two fully vaccinated individuals in New York who tested positive for COVID-19 . Though both recovered quickly at home, genomic data in those cases revealed multiple mutations in both viral samples, including a variant first identified in South Africa and Brazil, and another, which has been spreading in New York since November.
These findings in Israel and the United States also highlight the importance of tracking coronavirus variants and making sure that all eligible individuals get fully vaccinated as soon as they have the opportunity. They show that COVID-19 testing will continue to play an important role, even in those who’ve already been vaccinated. This is even more important now as new variants continue to rise in frequency.
Just over 100 million Americans aged 18 and older—about 40 percent of adults—are now fully vaccinated . However, we need to get that number much higher. If you or a loved one haven’t yet been vaccinated, please consider doing so. It will help to save lives and bring this pandemic to an end.
 Evidence for increased breakthrough rates of SARS-CoV-2 variants of concern in BNT162b2 mRNA vaccinated individuals. Kustin T et al. medRxiv. April 16, 2021.
 Vaccine breakthrough infections with SARS-CoV-2 variants. Hacisuleyman E, Hale C, Saito Y, Blachere NE, Bergh M, Conlon EG, Schaefer-Babajew DJ, DaSilva J, Muecksch F, Gaebler C, Lifton R, Nussenzweig MC, Hatziioannou T, Bieniasz PD, Darnell RB. N Engl J Med. 2021 Apr 21.
 COVID-19 vaccinations in the United States. Centers for Disease Control and Prevention.
COVID-19 Research (NIH)
Stern Lab (Tel Aviv University, Israel)
Ben-Shachar Lab (Clalit Research Institute, Tel Aviv, Israel)
NIH Support: National Institute of Allergy and Infectious Diseases