Why we can’t tell if warmer weather slows down the spread of coronavirus

(The Conversation) Many people believe that warm weather protects us from respiratory illnesses such as COVID-19. The concept of “catching a cold” in summer is counter-intuitive. Yet what does the data say about the effect of the weather on the spread of the coronavirus?

In our research, we set out to analyze if temperature influences the number of confirmed COVID-19 cases. Researchers around the world have been working on this question, and a number of politicians and public health officials have commented on the idea publicly. In the scientific literature, mixed results have been presented, with some studies finding that the weather influences the spread or severity of COVID-19, and others finding that it does not.

However, our research shows that, because of the unreliability of the available case count data, it is impossible to know whether people are more likely to contract COVID-19 in cold or hot weather at this stage. These data limitations may also affect analyses looking at whether other factors influence the spread of COVID-19. Here’s why.

- Advertisement -

Indonesia’s initial testing program was very small for a country of its size. EPA-EFE

The problem with the data

The data we have on COVID-19 only covers confirmed cases. For a COVID-19 case to be recorded, someone has to contract COVID-19 and be tested.

But testing has been insufficient. We don’t know exactly how many people have had the disease. In the early stages of the pandemic, the virus may have easily been mistaken for a cold or pneumonia and, because very few tests were available, only a sample of COVID-19 cases may have been confirmed.

Consider, for example, Indonesia. It has a population of 273 million, but only 70,000 tests were performed in the country before the end of April. With so much of the virus’s potential spread uncharted, it’s difficult to accurately determine what influences it.

- Advertisement -

And there’s another, more complex problem with the data – which is that changes in the number of confirmed cases could come from changes in how patients are selected for testing. In particular, factors influencing the spread of the virus, such as the weather, are likely to affect tests being carried out, too.

For example, it’s well established that common respiratory illnesses (such as the common cold and the flu) are weather sensitive and that patients with such illnesses are more likely to ask for a COVID-19 test because their symptoms are similar to those seen in COVID-19. Therefore, depending on the weather, there could be an influx of patients with COVID-like symptoms that do not have the disease, who end up using the limited number of tests available.

We do not know how large such an effect could be, but this makes it impossible to estimate the true influence of the weather on COVID-19. Even though there are more tests available now, most patients are still selected for testing based on whether they show COVID-like symptoms. Therefore, the incidence of other weather-sensitive respiratory diseases is still affecting the selection of who gets tested.

And the weather may also influence testing through other channels. For instance, the weather could increase the number of people hospitalized with weather-sensitive diseases that aren’t COVID-19 and so decrease the capacity of hospitals to take in other patients and test them for the virus.

For analysts, this means that an increase in the number of recorded cases could be due to an increase in the number of infections, but equally could be down to something else that changes who got tested in the population. If trying to judge the effect of the weather on COVID-19 by looking at numbers of confirmed cases, the above factors prevent any meaningful statistical analyses from being made.

he UK’s testing capacity rose sharply after lockdown measures were introduced in March. EPA-EFE

Other analyses could be affected

- Advertisement -

Our research suggests there’s a similar problem when trying to measure the effects of other factors on COVID-19, such as the effect of control measures. This is because most parameters influencing the spread of the disease are likely to have also influenced testing capacity and practices, having a knock-on effect on case numbers.

For instance, studies looking at the impact of lockdown measures face a similar issue, since testing practices changed before and after these policies were introduced. Most of the time, lockdown measures were accompanied with an increase in testing.

Policymakers and the public should therefore exercise great caution when interpreting the results from studies looking at the impact of the weather, or any other factor, on the spread of COVID-19 using case count data. This is likely to extend to analyses looking at confirmed deaths, since they are derived from confirmed COVID-19 cases.

While the data on COVID-19 cases makes it difficult to assess if the weather has an influence on the spread of the disease, it is by now evident that the virus has been able to spread in all parts of the world, including in very warm areas, such as Ecuador, Brazil and India. It continues to spread in warmer states in the US such as Florida, California and Texas.

Given the uncertainty about what can affect the confirmed case count of COVID-19, the safest option is to exercise caution and maintain appropriate social distancing while enjoying the good weather in summer.The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

- Advertisement -
Q Costa Rica
Q Costa Rica
Reports by QCR staff

Related Articles

COVID-19 in Costa Rica: 549 news cases; Dota reports infection after 159 days

(QCOSTARICA) This Wednesday, August 12, the Ministry of Health reported 549...

COVID-19 left Escazu without a municipal police

(QCOSTARICA) The canton of Escazu will be without a municipal police...

MOST READ

COVID-19 left Escazu without a municipal police

(QCOSTARICA) The canton of Escazu will be without a municipal police force until August 19, after a positive case of COVID-19 in an official...

Mayors promised some businesses to operate during closings

(QCOSTARICA) The Government committed to orange zone mayors easing vehicle restrictions and allow some businesses to operate during the closure phases (August 10 to...

25 years in prison for murder of the Spanish tourist in Tortuguero

(QCOSTARIC) Alvin Stanford Díaz Hawkings was sentenced to 25 years in prison on Monday for killing the Spanish tourist, Arancha Gutiérrez López, on August...

CCSS expects to begin human testing of equine serum in two weeks

(QCOSTARICA) The Caja Costarricense de Seguro Social (CCSS) expects in two weeks to start human testing of the equine serum developed as a possible...

Panama suspension of international flights continues

PANAMA CITY - On July 17, the Government of Panama extended the suspension of international commercial passenger and domestic charter flights, originally announced on...

El Salvador to give immunity passport to those who recovered from COVID-19

(Q24N) President Nayib Bukele on Monday announced that El Salvador will give immunity passports to people who have recovered from COVID-19. Bukele added that they...

Let's Keep This Going!

To be updated with all the latest news and information about Costa Rica and Latin America.

Log In

Forgot password?

Forgot password?

Enter your account data and we will send you a link to reset your password.

Your password reset link appears to be invalid or expired.

Log in

Privacy Policy

Add to Collection

No Collections

Here you'll find all collections you've created before.