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Will Warm Weather Slow Spread of Novel Coronavirus?

Posted on by Dr. Francis Collins

Summer gear and a face mask
Credit: Modified from iStock/energyy

With the start of summer coming soon, many are hopeful that the warmer weather will slow the spread of SARS-CoV-2, the novel coronavirus that causes COVID-19. There have been hints from lab experiments that increased temperature and humidity may reduce the viability of SARS-CoV-2. Meanwhile, other coronaviruses that cause less severe diseases, such as the common cold, do spread more slowly among people during the summer.

We’ll obviously have to wait a few months to get the data. But for now, many researchers have their doubts that the COVID-19 pandemic will enter a needed summertime lull. Among them are some experts on infectious disease transmission and climate modeling, who ran a series of sophisticated computer simulations of how the virus will likely spread over the coming months [1]. This research team found that humans’ current lack of immunity to SARS-CoV-2—not the weather—will likely be a primary factor driving the continued, rapid spread of the novel coronavirus this summer and into the fall.

These sobering predictions, published recently in the journal Science, come from studies led by Rachel Baker and Bryan Grenfell at Princeton Environmental Institute, Princeton, NJ. The Grenfell lab has long studied the dynamics of infectious illnesses, including seasonal influenza and respiratory syncytial virus (RSV). Last year, they published one of the first studies to look at how our warming climate might influence those dynamics in the coming years [2].

Those earlier studies focused on well-known human infectious diseases. Less clear is how seasonal variations in the weather might modulate the spread of a new virus that the vast majority of people and their immune systems have yet to encounter.

In the new study, the researchers developed a mathematical model to simulate how seasonal changes in temperature might influence the trajectory of COVID-19 in cities around the world. Of course, because the virus emerged on the scene only recently, we don’t know very much about how it will respond to warming conditions. So, the researchers ran three different scenarios based on what’s known about the role of climate in the spread of other viruses, including two coronaviruses, called OC43 and HKU1, that are known to cause common colds in people.

In all three scenarios, their models showed that climate only would become an important seasonal factor in controlling COVID-19 once a large proportion of people within a given community are immune or resistant to infection. In fact, the team found that, even if one assumes that SARS-CoV-2 is as sensitive to climate as other seasonal viruses, summer heat still would not be enough of a mitigator right now to slow its initial, rapid spread through the human population. That’s also clear from the rapid spread of COVID-19 that’s currently occurring in Brazil, Ecuador, and some other tropical nations.

Over the longer term, as more people develop immunity, the researchers suggest that COVID-19 may likely fall into a seasonal pattern similar to those seen with diseases caused by other coronaviruses. Long before then, NIH is working intensively with partners from all sectors to make sure that safe, effective treatments and vaccines will be available to help prevent the tragic, heavy loss of life that we’re seeing now.

Of course, climate is just one key factor to consider in evaluating the course of this disease. And, there is a glimmer of hope in one of the group’s models. The researchers incorporated the effects of control measures, such as physical distancing, with climate. It appears from this model that such measures, in combination with warm temperatures, actually might combine well to help slow the spread of this devastating virus. It’s a reminder that physical distancing will remain our best weapon into the summer to slow or prevent the spread of COVID-19. So, keep wearing those masks and staying 6 feet or more apart!


[1] Susceptible supply limits the role of climate in the early SARS-CoV-2 pandemic. Baker RE, Yang W, Vecchi GA, Metcalf CJE, Grenfell BT. Science. 2020 May 18. [Online ahead of print.]

[2] Epidemic dynamics of respiratory syncytial virus in current and future climates. Baker RE, Mahmud AS, Wagner CE, Yang W, Pitzer VE, Viboud C, Vecchi GA, Metcalf CJE, Grenfell BT.Nat Commun. 2019 Dec 4;10(1):5512.


Coronavirus (COVID-19) (NIH)

Bryan Grenfell (Princeton University, Princeton, NJ)

Rachel Baker (Princeton University, Princeton, NJ)


  • Camilo Colaco says:

    possibly, but treating the coagulopathy seen in CoVID patients early with anticoagulants may save more lives

  • John Hasty says:

    Will the COVID-19 vaccine help prevent the “common cold”?

    • Josey Barger says:

      Scientifically no, Covid-19 is a more advanced cell than your “common cold.” Covid-19 is more infectious, and, with that, the antibodies are too. They specifically go after the Covid-19 cells and nothing more.

  • F. George Dunham, III says:

    Yes, you must reach some level of group immunity before climate plays a significant role. It’s in the math …

  • DR. SAUMYA PANDEY, PH.D. says:

    Covid-19 viral transmission trends in climatic/seasonal transitions primarily peak summer months May-June and subsequently in Fall have been well-depicted with sophisticated computer-based algorithms/predictive simulation models for designing eventual patient-friendly cost-effective globally acceptable standard research protocols warranting long-term future collaborations in the ever-expanding viral pathogenesis-epidemiology-public health and immunobiology/biomedical sciences/public health areas.
    Overall, a thought-stimulating expert commentary with critical research insights from my American NIH USA-Director Dr. Collins!

    • vincent frishee says:

      it’s not mere “heat” or “summer climate”…it’s exposure to UV rays to produce Vitamin D. More people are outdoors in summer with less clothing covering arms and legs etc. In winter people are 40% to 80% deficient in Vitamin D. Most flu cases in winter would be reduced substantially if people took Vitamin D supplements. But that’s too logical and inexpensive when pharma ‘science’ can get people to spend lots of money on flu drugs and OTC medicines.

  • Aaron Chapman says:

    Very interesting. The blog went in-depth, and I could understand everything well!

  • Sparky says:

    However, if I understand this thoroughly, all of this data remains hypothetical and at best is nothing but an educated best guess. Yes? Is that enough to justify major economic destruction from shutting it down? Do you have an algorithm that can compare loss of life from the destruction of a state to the loss from a virus that the CDC has just downgraded to 0.04% mortality?

    • Tobias says:

      God, I don’t know why I’m responding to people on the internet but here we go.
      To Sparky and anyone who poses similar arguments: even if the stated death rate is correct (0.04% mortality), remember that this is a novel virus. EVERYONE is susceptible to it. Given that the population of the United States is approximately 330 million, that means about 13.2 MILLION PEOPLE WILL DIE of COVID-19 in the US alone if we completely reopen the country and allow it to spread.

      • Brevity is... says:

        Can someone clarify the Fatality Rate that is being cited?
        Sparky said 0.04% (will we pass that # by the end of the year?), While Tobias said 4% (100x) what Sparky was citing.

        4% seems high (I hope it’s not 4%)..

        Are we talking CFR which may be 4% or IFR which may prove to be sub 1% but won’t be known for sometime?

        Thanks for the clarification

    • Caroline says:

      I love your insight and answer Sparky. You are so on the money. All of these restrictions have caused WAY MORE HARM than good. So sad to see the increased suicide rate, job losses, school closures, increase in domestic violence, abuse of the unemployment system, and many politicians taking away our freedom and religious liberty.

  • Mike says:

    I realize no one knows for sure how the virus is going to behave, but I wonder if experts have a strong hunch whether we will see a huge peak/wave in the fall like the 1918 flu pandemic, or whether it’s more likely to be a slow burn. Dr. Osterholm said he’d be worried if cases suddenly dropped off because that could be a sign of an upcoming fall peak, but cases are still increasing.

  • vincent frishee says:

    it’s not the mere ‘heat’ or ‘summer climate”….it’s specifically exposure to UV rays that produce Vitamin D as more people allow skin exposure due to wearing less clothing covering arm and legs etc. Americans are 40-80% deficient in Vitamin D. If Vitamin D supplements were recommended in winter cold and flu cases would be reduced substantially. But that goes against the pharma ‘science’ resulting in millions spent on cold/flu drugs and OTC remedies. Not sure?…well perhaps after 100 years pharma profiting it’s time do a real (independent) clinical study.

  • pastordavej says:

    After the inaccurate “models” regarding the number of deaths caused by COVID, I don’t trust any of their models. There are too many variables for any model to anticipate in their calculations. For example, now some scientists are saying that people with type A blood are the most likely to die. Who could have anticipated that variable in their models?

  • Deepak D. says:

    Thanks for sharing an informative article. As now it’s very warm weather and day by day corona cases seem to be increasing very quickly, you can’t be sure that warm weather will slow down coronavirus …

  • Paul says:

    I think how weather can reduce the deaths of covid-19. Because i see, there are less deaths for people living in hot weather. I don’t know whether it makes any sense.

  • CCI says:


  • Chris Preston says:

    Maybe someone might be able to explain how the science states that a virus cannot survive in 80+ and -30 weather. A lot of talk but no data released. Why? I think to control.

  • Arihaan says:

    Would a heat vaccine help stop Covid?

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