Clinical Public Health

Period. 15 - 21 September 2020

The WHO has reported a significant drop in flu activity in the Southern Hemisphere which would typically be in the middle of its influenza season. There were initial concerns that the decline in reported flu cases reflected reduced testing capacity or strained health care systems attempting to respond to COVID-19. The WHO, however, maintains a network of national research centres, including Australia, Argentina, South Africa, Paraguay, New Zealand and Chile. While the total number of influenza tests fell by 20% in these six countries, the share of positive tests dropped to record lows that are “unprecedented,” according to the South African National Institute for Communicable Diseases.

An article in the Lancet credits the enhanced hygiene and physical distancing measures that many countries are undertaking as part of their COVID-19 response efforts for the reduction in reported flu cases. The author, meanwhile, also warns of the potential impact of altered infection testing priorities, health-care personnel capacity, and health seeking behaviours during the pandemic should not be ignored. At the same time, the record-low flu season flu in the Southern Hemisphere has also created a potential blind spot, as less circulating influenza virus means fewer clues about the genetic variants most prevalent and likely to contribute to the coming flu season in the Global North.

One strategy to reduce the likelihood of a double epidemic would be to expand influenza vaccination programs, both in reducing the flu burden and to counteract their facilitatory impact on COVID-19. The Director of the CDC has urged local health authorities to scale up flu vaccine programs, particularly among high-risk populations such as children and the elderly, in order to reduce the overall burden on health systems. In the U.S., flu vaccine production is expected to increase by 13% to 200 million doses, with two new quadrivalent flu vaccines specifically developed for seniors this year. The CDC has also developed a new diagnostic test that allows public health labs to test for both influenza and COVID-19, that would be used for surveillance purposes to track how both diseases are spreading and whether they can co-circulate.

As advanced economies have been able to place large order for the influenza vaccine, however, there are concerns that the further increase in global demand could lead to a vaccine shortage. Public health experts have also warned that entering the winter without a Coronavirus vaccine could present challenges for countries where pressures to reopen schools and businesses could result in COVID-19, influenza and seasonal cold co-circulating in indoor spaces. That caution is echoed by a pre-publication on MedRXiv that models the impact of the coming flu season on the spread of COVID-19. The study, currently under peer-review, uses a population model to project an estimated 2 to 2.5-fold increase in novel Coronavirus transmission associated with influenza during the period of co-circulation.

This development is part of the digest;