Seasonal COVID-19 Outbreaks

Today, Dr. Anthony Fauci warned that the SARS-CoV-2 virus can have a seasonal infection cycle.

There have been numerous reports and some correlative studies that suggest that coronavirus will die down in the summer in the United States as the weather gets warmer.

However, Dr. Fauci mentioned that we are starting to notice outbreaks of COVID-19 in countries in the southern hemisphere. As these countries go into their winter season, Dr. Fauci mentions that it will be inevitable that we will face another coronavirus infection outbreak in the fall. More details are available here.

The current COVID-19 pandemic has outbreaks along the same latitude line, suggesting that there is an optimal temperature and humidity range for spreading coronavirus (Sajadi et al. SSRN 2020).

Sajadi et al. SSRN 2020.

Sajadi et al. showed that virus transmission was significant in cities with an average temperature between 5 and 10 degrees Celsius and a specific humidity between 2 and 7 g/kg.

Sajadi et al. SSRN 2020.

Based on this, they predicted that the cities most likely to be affected by COVID-19 in March to April, notably London, Berlin, and New York. This is exactly what we have noticed, where these cities have been hit the hardest by the disease.

Sajadi et al. SSRN 2020.

These areas are exactly where the cases have been rising the fastest.

Source: NYTimes. March 26, 2020
Source: https://nextstrain.org/ncov

However, the concerning part of this graph is that we are starting to see outbreaks in Australia, Brazil, and Democratic Republic of the Congo, southern hemisphere countries about to enter into their winter season.

Sajadi et al. speculated that perhaps like the 2003 SARS-CoV virus, the current pandemic may not sustain itself in the summer and may disappear. However, the increasing outbreaks in the Southern Hemisphere may lead to the creation of seasonal peaks just like influenza.

The influenza virus is extremely at adept at evading the immune system and creating new mutant strains. Consequently, the antibodies we make against the influenza virus in one year may not be effective for the mutant influenza virus the next year. We are more likely to get sick from influenza n the winter months, when we are often indoors, in crowded areas with ambient temperature and indoor heating, and more likely to air travel. This is why we are recommended to get yearly flu vaccine shots.

We already know that COVID-19 is rapidly evolving and mutating, with some strains more virulent than others. Just like influenza, the coronavirus may persist at lower levels in tropical regions and then rise again next fall. We may face a grim reality in which we face yearly coronavirus outbreaks.

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