WHO Recommends New Composition Of Flu Vaccines For 2023 Influenza Season: Why We Need Periodic Update Of Vaccines?

WHO has asked national vaccine regulators and pharma companies to update flu vaccines for the 2023 southern hemisphere influenza season.

The World Health Organization (WHO) has issued new recommendations for the viral composition of influenza vaccines for the 2023 southern hemisphere influenza season. National vaccine regulatory agencies and pharmaceutical companies are encouraged to consider the new recommendations while developing, producing, and licensing flu vaccines for the next influenza season.

In its release, the WHO stated that the new composition of influenza vaccines was issued based on the analysis of virus surveillance data produced by the WHO Global Influenza Surveillance and Response System (or GISRS). The data was analysed by a group of experts from WHO Collaborating Centres and WHO Essential Regulatory Laboratories.

Why there's a need to update the existing flu vaccines?

According to WHO, influenza viruses are constantly evolving and hence it is necessary for flu vaccines to be updated periodically so that the vaccines are effective against the new and emerging strains.

Every year, around a billion of people worldwide get infected with seasonal influenza and "the threat of an influenza pandemic is ever-present," the UN health agency said highlighting the importance of continues monitoring of circulating respiratory viruses.

GISRS, a global network of over 150 laboratories in 127 countries, conducts a year-round surveillance of respiratory viruses, including influenza. Based on the analysis of this surveillance data, WHO issues vaccine composition recommendations twice a year.

New Flu Vaccines will have the following components

As per the WHO's new recommendations, quadrivalent vaccines for use in the 2023 southern hemisphere influenza season should contain the following components:

For egg-based vaccines

• an A/Sydney/5/2021 (H1N1) pdm09-like virus
• an A/Darwin/9/2021 (H3N2)-like virus
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus, and
• a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

For cell culture -or recombinant-based vaccines

• an A/Sydney/5/2021 (H1N1) pdm09-like virus
• an A/Darwin/6/2021 (H3N2)-like virus
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus, and
• a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

The organization suggested that trivalent vaccines be updated with the following components for use in the next influenza season:

For egg-based vaccines

• an A/Sydney/5/2021 (H1N1) pdm09-like virus,
• an A/Darwin/9/2021 (H3N2)-like virus, and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

For cell culture- or recombinant-based vaccines

• an A/Sydney/5/2021 (H1N1) pdm09-like virus,
• an A/Darwin/6/2021 (H3N2)-like virus, and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

WHO added that GISRS will also be monitoring other respiratory virus threats, including COVID-19.