South-East Asia: Influenza virus sharing in a time of COVID-19

In South-East Asia, countries are resuming influenza virus sharing activities following severe disruption from the COVID-19 pandemic, and successfully contributing to World Health Organization’s (WHO) bi-annual seasonal influenza vaccine composition meetings.

Influenza virus sharing is vital to global preparedness to facilitate pandemic risk assessment, develop candidate vaccine viruses, update diagnostic reagents and test kits, and determine resistance of influenza viruses to antiviral medicines.

In WHO’s South-East Region, National Influenza Centres (NICs) have long shared viruses with WHO Collaborating Centres (CCs) as part of their routine influenza surveillance activities.

But their efforts were severely disrupted during the COVID-19 pandemic, especially during the early stages as staff and resources across the surveillance system were diverted to support an emergency response.

Specific challenges included: a lack of influenza positive samples; poor geographical or temporal representativeness of collected specimens (especially during periods of  lockdown); and excessive workloads, which caused delays in influenza testing (so specimens may have been collected but they were not processed) and created operational difficulties in isolating viruses for shipment.

Specimen collection media (viral transport medium) also posed a challenge during the pandemic as the transport medium used for SARS CoV-2 was not appropriate for influenza.

In those countries that quickly resumed influenza surveillance to pre-COVID-19 levels, an additional challenge was the very low transmission of seasonal influenza seen during the pandemic, which resulted in low numbers of specimens shared.

To re-prioritize virus sharing in the region, participants at two regional influenza meetings shared their experiences of influenza surveillance during the pandemic, discussed the latest WHO guidance for adapting influenza surveillance systems to also monitor SARS-CoV-2 and considered a range of context-specific needs and priorities.

Their deliberations led to four key recommendations:

-Expand influenza surveillance to non-sentinel sites, with subsequent reporting to  FluNet, to increase the chances of identifying influenza activity and collecting samples for testing and virus isolation.

-Advocate for integrated influenza and SARS CoV-2 surveillance, including the use of multiplex kits.

-Share all available influenza specimens with a WHO CC in a timely manner, even if there is only one specimen.

-Use two virus transport media—with and without influenza virus inactivation substances—to support the collection of samples with viable influenza viruses, local testing and subsequent shipment to an NIC.

WHO has been supporting countries to implement these recommendations. It has provided need-based logistical support through its Regional Office for South-East Asia and the Shipping Fund Project. WHO has also sent out periodic reminders to prompt virus sharing.

The result is that all South-East Asia countries with influenza-positive specimens managed to share viruses at least once with WHO CCs collecting data to inform WHO’s biannual vaccine composition meetings. The region shared nine shipments for the September 2020 meeting, three for the February 2021 meeting and five shipments for the September 2021 meeting.

Now plans are underway to further improve virus sharing in the region, including through a monthly follow-up process for influenza positives reported to WHO, and by providing NICs with systematic updates on streamlining virus sharing processes, with a focus on ensuring representativeness and timeliness.