August 2023

Recently, there has been a spike in influenza cases, both locally and abroad. One of the reasons may be attributed to immunity gap – at any given time, people are exposed to common viruses such as influenza; however, the extended lockdown during the pandemic may have resulted in the immunity not developing, making them more susceptible to the virus now. But, is that the only reason? Or is there a more contagious influenza strain circulating?

Globally, while not related to the increase in cases mentioned above, new trends are starting to emerge related to different influenza strains. In certain countries, H3N2 has surpassed H1N1 and Covid cases. H3N2, which can be traced back to the 1968 pandemic, can cause mild to severe disease.

There have also been reports about the highly pathogenic avian influenza, H5N1 being found in animals previously not affected. In July, South Korea confirmed two cases of cats with H5N1 infection. H5N1 was also confirmed in two fox cubs in July, the first time the virus has been found in wild mammals in Northern Ireland.

The outbreaks among mammals were not only limited to South Korea and Northern Ireland, but affected more than 10 countries. Both sea and land mammals have been infected, including seals in the US, sea lions in Peru and Chile, and farmed mink in Spain with close to 30 species known to have been affected. As mentioned above, H5N1 virus has also been detected in domestic animals such as cats and dogs in several countries.

Should we be concerned that the virus is spreading among other animals? Avian influenza virus typically spreads among birds, but the detection of H5N1 among mammals - which are biologically closer to humans - raises concern that given the high mutation rate of influenza virus might enable it to adapt to infect humans, though there is no evidence of this currently. Due to the infection in mammals, this could also lead to the emergence of recombinant viruses, new viruses that could be more harmful to animals and humans.

Is there a risk of animal-to-human or human-to-human transmission? So far, the virus does not appear to be able to transmit from animal to human, or from one person to another, but strong surveillance needs to be in place to detect any changes. WHO and other agencies are closely monitoring the evolution of these viruses. In the past, human cases associated with H5N1 avian influenza were isolated and no human-to-human transmission were identified in any of the cases. Though this is reassuring, we still cannot let our guard down.

What can we do to protect ourselves? Controlling avian influenza in birds will mitigate the risk of transmission. Anyone handling birds should be extra cautious. If a person comes across a dead or a sick bird, they should avoid handling it directly. For those not in the poultry industry, even if H5N1 does not reach our shores, influenza outbreaks can still occur. Applying lessons from the pandemic, we should get tested quickly if any symptoms are displayed. Similar to other viruses, an extremely effective way to keep the virus at bay is to stay ahead of vaccinations, to keep you and your loved ones safe.

Text: Dr. Kumitaa Theva Das, Department of Biomedical Sciences, Advanced Medical and Dental Institute (IPPT), Universiti Sains Malaysia