COVID-19 Reduced the Southern Hemisphere’s Flu Season
According to the World Health Organization (WHO), the global responses to the COVID-19 pandemic led to fewer influenza virus cases being reported during the April to August 2020 time-period.
This reduction in flu cases throughout the Southern Hemisphere as of September 25, 2020, was related to travel restrictions, coronavirus mitigation strategies, and social distancing measures.
Specifically, the WHO reported in the temperate zones of the southern hemisphere, very few influenza virus detections were reported and detection rates remained below seasonal epidemic thresholds despite continued or even increased testing for influenza in some countries.
In the southern cone of South America, influenza A viruses predominated, with the majority being A(H1N1)pdm09, followed by influenza B, with the great majority being B/Victoria/2/87 lineage viruses.
In Southern Africa, influenza A(H1N1)pdm09 viruses were predominant, followed by influenza B viruses, with no detection of A(H3N2) viruses.
And, influenza activity was very low in reporting countries in Oceania with co-circulation of influenza A and influenza B viruses and predominance of influenza A(H1N1)pdm09.
Furthermore, influenza activity in tropical and subtropical countries was generally low. In most reporting countries in the tropics and subtropics, there were very few or no detections of influenza viruses between April and September.
Of note, in Mexico influenza activity was high in February and March and decreased in April.
In Africa, South America, the Caribbean, Central America, and tropical countries of Asia, influenza A(H1N1)pdm09 was predominant followed by influenza B/Victoria/2/87 lineage and A(H3N2), with low numbers of B/Yamagata/16/86 lineage viruses reported.
During this period of 2020, influenza A viruses were predominant in most countries.
Globally, co-circulation of both A(H1N1)pdm09 and A(H3N2) viruses was reported by most countries, areas, and territories, with A(H1N1)pdm09 being dominant in most reporting countries. In Southern Africa, A(H1N1)pdm09 was the only subtype reported.
However, A(H3N2) viruses circulated in higher proportions in some countries in Africa, Asia, and Europe, notably in Burkina Faso, Mali, and Mongolia, where it was the only A subtype reported.
And influenza B viruses generally circulated at lower levels than influenza A viruses.
However, in some countries in the Americas (Belize, El Salvador, Nicaragua, Panama, Paraguay, and Trinidad and Tobago), Europe (Ireland), Africa (Niger and Senegal) and Asia (Azerbaijan, Iran(Islamic Republic of), Iraq, Israel, and Kuwait), influenza B viruses predominated.
Of the influenza B viruses, the B/Victoria/2/87 lineage predominated with very few B/Yamagata/16/88 lineage viruses detected.
Regarding flu vaccine effectiveness (VE) estimates from the 2019-20 season in the USA indicated that vaccination was more effective against group 5A-187A viruses (41%) than against group 5A-156K viruses (7%). A similar VE trend was observed in Europe, says the WHO.
For the 2020-2021 flu season in the Northern Hemisphere, the U.S. CDC has authorized various influenza vaccines, including a nasal spray option.
The most common flu shot for the new influenza season in the Northern Hemisphere are quadrivalent vaccines that protect people against 4 viruses; influenza A (H1N1) virus, influenza A (H3N2) virus, and 2 influenza B viruses, said the CDC on August 21, 2020.
The CDC encourages most people over 6 months of age to get vaccinated every flu season since influenza infections can create severe consequences.
PrecisionVaccinations publishes research-based flu shot news.