COVID-19 the illness caused by the SARS-CoV-2 virus, is likely to become a seasonal disease in countries with temperate climates. This has been suggested by a new review published in Frontiers in Public Health.
“COVID-19 is here to stay and it will continue to cause outbreaks year-round until herd immunity is achieved. Therefore, the public will need to learn to live with it and continue practicing the best prevention measures, including wearing of masks, physical distancing, hand hygiene and avoidance of gatherings,” said senior author of the study Dr. Hassan Zaraket, of the American University of Beirut in Lebanon.
Collaborating author Dr. Hadi Yassine, of Qatar University in Doha, affirms and states that there could be multiple waves of COVID-19 before herd immunity is achieved.
We know that many respiratory viruses follow seasonal patterns, especially in temperate regions. For instance, influenza and several types of coronaviruses that cause common cold are known to peak in winter in temperate regions but circulate year-round in tropical regions.
The researchers explain that virus survival in the air and on surfaces, people’s susceptibility to infections, and human behaviours, such as indoor crowding, differ across the seasons due to changes in temperature and humidity. These factors influence transmission of respiratory viruses at different times of the year.
However, in comparison to other respiratory viruses such as the flu, COVID-19 has a higher rate of transmission (R0), at least partly due to circulation in a largely immunologically naive population.
This means that unlike the flu and other respiratory viruses, the factors governing seasonality of viruses cannot yet halt the spread of COVID-19 in the summer months. But, once herd immunity is attained through natural infections and vaccinations, the R0 should drop substantially, making the virus more susceptible to seasonal factors.
Such seasonality has been reported for other coronaviruses, including those which emerged more recently such as NL63 and HKU1, which follow the same circulation pattern like influenza.