We, at least I, have started hearing more frequently that the bird flu virus, H5N1, has been causing concern around the world. The virus seems not to be satisfied in keeping wild birds and poultry as its main hosts anymore. H5N1 has started to spread around mammals, and as we know, this virus is a nasty one.
H5N1 is a type of influenza virus that causes severe respiratory disease in birds and it is highly infectious, wreaking havoc in these animals for 25 years. There have been occasional cases of human H5N1, but the transmission from person to person is more difficult. Although the virus can bind to human lung cells, it attaches deeply into the respiratory tract to be coughed and spread. However, when do people get infected, the mortality rate is around 60%.
More recently, there have been several reports of mammals such as foxes, minks, otters, and sea lions becoming infected by the virus. This confirms the jump, spillover, of the virus from birds to mammals. WHO, at the moment, states that the human risk is low. However, it advises that countries should strengthen surveillance where humans and wild or farmed animals interact.
According to WHO’s report of the cumulative number of confirmed human cases for H5N1; in a space of 10 years, there have been 868 cases of the infection and 457 deaths. (Graph below)
If the virus is jumping from avians to mammals, it is not difficult to think that the virus is mutating and its genetic profile is diverging even further from what it used to be when it started. When the Spanish outbreak of bird flu occurred in minks from one farm in October 2022, genetic analysis was carried out. They noticed the viruses from the mink farm were different from H5N1 viruses characterised before in Europe. There is an uncommon mutation in a certain gene that may impose public health concern. This mutation confers human receptor recognition.
Avian Flu in the UK
In the UK, since October 2022, there have been 173 cases of the highly pathogenic avian influenza (HPAI), H5N1. 164 cases in England, 21 cases in Scotland, five cases in Wales and one case in Northern Ireland. As of February this year, the presence of this virus was confirmed in commercial poultry at premises near Thetford and Breckland, Norfolk. The areas of Scotland where this virus has been found can be seen in the picture below – taken from the APHA Interactive Avian Influenza Disease Map. The risk levels of HPAI influenza is assessed as very high in Great Britain.
Interesting to learn, is the fact that poultry or captive birds can’t be vaccinated against the virus in the UK. The reason being, the rapid mutation of the virus and the transmission amongst even vaccinated animals. There are practical issues in performing the vaccination and there is no proven efficacy of the vaccine in other avian species.
Have the UK learned with previous pandemics to strengthen its preparedness?
Covid-19, our most recent pandemic still speaks loudly when it comes to preparedness. The cumulative confirmed Covid-19 cases in the UK as of the 21st of February this year is 24.34mn and 360,569 per million people. In Scotland, in the past week, 1,508 new cases were identified. These numbers are lower than true numbers due to limited testing. From these numbers, 2.0mn people in private households self-reported having long Covid at the beginning of January 2023.
We are on the 3rd year since the pandemic has started and people with a debilitating disease still have to self-report for long Covid remotely. There is not an efficient data collection to divide these individuals into groups, neither a funding directed to targeted therapy. If we consider that Covid-19 is a vascular disease, I consider a failure in preparedness. Simple mitigations that could be carried in the beginning and still in the present time have been disregarded.
Therefore, what does make me believe that we will be ready for the next pandemic to come? Have any PPE issues been resolved? How will the NHS cope? Have we evolved with regards to tracking and tracing?
From October to December 2022 there were 2,085 exposure episodes to Avian flu (where a person gets in direct contact with an infected bird). The data on incidents is incomplete. Data was collected in only 29% of the incidents. PPE was used in 27.3% of exposures. Antiviral prophylaxis applied in 15.9% of exposures. Symptoms were reported in 4.3% of exposures and swabs carried out in 77.4% of those eligible. There was no detection of the virus in humans for the specified time. The UK has also detected a mutation that is associated with advantages for mammalian spillover events.
The ability to identify the risk of asymptomatic or mild disease is poor, since there is limited testing in human contacts of infected birds. Detection of human-to-human transmission can be delayed as sub-typing surveillance in the NHS is incomplete, so there is not enough information to assess the occurrence in the limited numbers of transmission between humans, such as the ones within households. The indicators of increasing risk to human health are considered as low confidence assessment.
There is no doubt that more research is needed to evaluate the gaps still present for an efficient surveillance. It is not time to be fuzzy warm. It is time instead to focus on surveillance efforts by testing without failure and by sequencing of samples. Mainly after the very recent sad news of the death of an 11 year old girl in Cambodia followed by 12 new infections.