Public health experts in the Northern Hemisphere are predicting a fall/winter respiratory virus season for the ages — one that highlights the importance of tools in the fight against global surveillance efforts and vaccines. influenza (flu) and COVID-19.
Understanding the Impact of COVID-19 on Earlier Seasonal Flu covid-19 pandemicThe annual respiratory virus season in northern and southern climates was a pandemic characterized by rapid increases in influenza (flu) rates and influenza-like illness beginning in mid-fall and peaking in mid-winter. and winding up in mid-spring.
The previously predictable pattern of influenza activity in the global north and south has become somewhat unpredictable in post-pandemic seasons.
In the United States, approximately 36 million infections, 390,000 hospitalizations, and 25,000 deaths fever were reported during the 2019–20 season.
In contrast, 2020-21 saw minimal influenza activity, while the 2021-22 season saw a four-fold decline in activity compared to the prior season.Epidemic season’s.
implementation of strict public health measures during covid-19 pandemic It was instrumental in reducing the incidence of flu and flu-like illnesses during the past two respiratory virus seasons in both hemispheres.
However, the easing of these measures is expected to fuel a tidal wave of respiratory virus infections in the coming weeks.
These infections include influenza, SARS-CoV-2 and respiratory syncytial virus (RSV), which most often affect children.
Influenza in the Southern Hemisphere
Despite the impact of COVID-19 on global health and almost negligible levels of seasonal influenza activity over the past two years, the Southern Hemisphere is expected to experience a major shift in influenza activity during 2022. respiratory virus weather.
Unlike seasonal influenza, COVID-19 behaves primarily as a pandemic virus with simultaneous, high-level viral transmission in all parts of the globe (Source: Pexels)
Beginning of season in Chile influenza B activity in January, followed by a relative lull in March and April, and then a surge in influenza A that peaked in June.
In contrast, Australia’s flu season began in March, peaked on record in June, and was dominated by influenza A throughout.
What’s in store for fall and winter?
Unlike seasonal influenza, COVID-19 behaves primarily as a pandemic virus with simultaneous, high-level viral transmission in all parts of the world. COVID-19 Activity may be “seasonal” in some cases, with higher rates of transmission during the fall and winter months when people are often indoors and, as a result, have less social-distancing.
The 2022 Southern Hemisphere experience serves as a harbinger for what to expect during the 2022-23 respiratory virus season in northern climates.
In the north, the respiratory virus season is already off to an early and blazing start, especially in the US and Canada, and is set to wreak havoc on health care systems that are already grappling with the effects of COVID-19 .
Importance of influenza vaccination Vaccination is one of the most effective public health interventions in our fight against influenza and COVID-19.
recommendations on the composition of flu vaccines They are made biennially by the World Health Organization (WHO), several months before the incoming respiratory virus season in each respective hemisphere.
However, licensure of influenza vaccines generally falls under national jurisdiction. Similar vaccine formulations are approved for use in the US, Canada, the United Kingdom and other northern countries, and are now widely available.
fever The vaccine composition for the 2022-23 respiratory virus season in northern latitudes is based on surveillance of influenza virus transmission during the most recent respiratory virus season in the Southern Hemisphere.
The World Health Organization recommends both quadrivalent vaccines (containing four strains) and trivalent vaccines (containing three strains), with no formulation preferred.
The quadrivalent vaccine contains two inactivated strains of influenza A (H1N1 and H3N2) and two inactivated strains of influenza B. The trivalent vaccine is identical with the exception of a single inactivated strain of influenza B.
How effective are flu shots?
Vaccine-mediated protection against influenza infection, severe illness, and death has broad public health implications, yet is often misunderstood.
Vaccine effectiveness varies from one respiratory virus season to another and depends on several factors, including the degree of vaccine mismatch with circulating strains, the use of high-dose versus standard-dose. VaccinesPrior influenza illness or vaccination, age, general health status, and public health measures such as social distancing, use of medical masks, and travel restrictions.
Flu vaccines provide greater protection against influenza B and influenza A H1N1 subtypes, with less effectiveness against influenza A H3N2 subtypes.
These infections include influenza, SARS-CoV-2 and respiratory syncytial virus (RSV), which most often affect children (Source: Getty Images/Thinkstock)
Research has shown that the effectiveness of standard-dose flu vaccines in preventing severe influenza illness during the 2019-20 US respiratory virus season was highest among young adults (60 percent), relatively low among middle-aged adults (20 percent). percent) and slight or negligible in the elderly.
High-dose vaccines improve effectiveness by up to 30 percent in the elderly. Therefore, people 65 years of age or older should receive the high-dose quadrivalent vaccine.
Other infection control precautions should be taken along with the flu shot. social distancingIndoor masking and frequent hand washing.
Do I really need a flu shot?
You can get the flu shot along with the COVID-19 shot.
Influenza vaccines are believed to be safe and effective in almost all individuals, despite a lack of strong evidence for safety in very young children and the elderly.
Their use is similar to the protection from wearing a seatbelt; You won’t necessarily be involved in an accident, but if you are, your chances of survival and protection from serious injury are greater than without their use.
During the 2019–20 respiratory virus season in the US, influenza vaccination prevented more than 100,000 hospitalizations and more than 6,000 deaths.
Given the expected burden of influenza illness and the ongoing COVID-19 pandemic, the benefits of vaccination are likely to be greater during the current respiratory viral season than in years past.
What is the role of the COVID-19 booster?
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For COVID-19, the effectiveness of the two-dose primary vaccine series and single booster in preventing hospitalizations is near 90 percent, but gradually declines to about 65 percent over the course of four to five months following the final vaccine dose. percentage falls.
Bivalent vaccine boosters may serve as a means of vaccine-induced protection Immunity Against the new variant of SARS-CoV-2.
COVID-19 vaccines remain part of an effective strategy to combat the next wave of infections.
The latest bivalent vaccines manufactured by Pfizer and Moderna are recommended as boosters for individuals who have had at least two primary COVID-19 vaccinations.
Bivalent vaccines are believed to be more effective against the dominant BA.4 and BA.5 omicron subvariants of SARS-CoV-2 than the original mRNA vaccines, but comparable in effectiveness to first-generation bivalent vaccines that target the original strain. do and ba.1 omicron subvariant,
The age-based and time-based eligibility criteria for these boosters are slightly different in the US, Canada and Europe.
Influenza and COVID-19 are expected to advance during the current respiratory virus season in northern climates.
Vaccination along with personal protective measures is the best means of staying healthy.
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