Dr. Youssef Dawood‏‏

WHO Chief Scientist Jeremy Farrar has voiced significant concern over the recent spread of avian influenza among cattle in the US. The US has reported only two human cases of the H5N1 avian flu strain in connection to cattle, but a wider outbreak could be catastrophic. During previous outbreaks, one in two infected individuals died, which suggests that H5N1 can be more virulent than COVID-19. Since this avian flu virus was first discovered nearly three decades ago in China, approximately 860 people across 23 countries, including China, Egypt, Vietnam, and Turkey, have contracted H5N1 from birds. There has been a total of 463 fatalities during those three decades—a mortality rate of around 52 percent.Key ObservationsWe can draw several observations about the current cases of avian influenza in the US and &nbsp;whether this could potentially escalate into a global pandemic:1. Concerns over Geographic Spread in the US: The avian influenza virus, which was originally confined to birds, has also spread to cattle. The first human case in the US in connection to avian flu in cattle was reported in April 2024. As of late March 2024, H5N1 has been detected in about 200 cattle across 36 dairy herds in US states including Colorado, South Dakota, Kansas, Michigan, North Carolina, Idaho, Texas, Ohio, and New Mexico.2. Rapid Virus Spread among Birds and Cattle: The rapid spread of avian flu among poultry in various global contexts has typically resulted in farmers culling infected animals. In early April 2024, a Texas poultry farm culled 1.5 million chickens in order to contain the virus. However, there have been no reports of cattle culling, as avian flu is not yet as lethal in cattle as it is in chickens and turkeys.3. Potential for International Spread?: In April 2024, a Texas farm worker contracted the virus, marking the first known transmission of avian flu from mammal to human. The worker only experienced mild conjunctivitis and recovered fully within a week. There are no confirmed cases of avian flu in cattle outside the US, although the WHO has warned of the risk of international spread via migratory birds.4. No Evidence of Other Transmission to Humans: US public health officials are monitoring cattle herds to understand the scope and speed of the virus’s spread. Since it is thought that cow milk and dairy products could be the most likely vectors of transmission to humans, the FDA has tested around 297 dairy products, including milk, cheese, and sour cream since April 2024. Although it found traces of the virus in 20 percent of 96 initial samples, further tests confirmed that pasteurization (a heating process used to eliminate pathogens and harmful bacteria in agricultural products) effectively kills the virus, thus mitigating any risk to consumers.Public health experts and authorities, including the CDC, therefore recommend that individuals consume only pasteurized dairy products to avoid avian influenza or bacterial infections such as salmonella and brucellosis. USDA tests on beef samples have returned negative for avian flu, although the FDA continues to advise against consuming raw beef.An Ongoing ThreatBased on these key observations, the following factors are likely to shape whether the US cases of H5N1 could become another global pandemic:1. US Government Response: Any potential global spread of H5N1 hinges on the response of the US government as the primary line of defense. US public health authorities and experts have stated that they have been studying avian influenza for decades, and that the COVID-19 pandemic has led to positive changes in disease outbreak preparedness. In late April 2024, the USDA began requiring all dairy cattle moving between states to be tested for avian influenza before transport. However, since intra-state farm testing remains voluntary, these precautions might be insufficient in containing disease spread to the extent the US authorities would prefer.2. How Other Countries Respond to the Virus Threat: In late April 2024, Colombia became the first country to restrict trade with the US due to avian influenza among cattle. Colombia limited imports of beef and beef products from states where cattle had been infected with the virus. In Mexico, which is a major market for US beef and dairy products, the Secretariat of Agriculture also intensified its monitoring of cattle entering the country for signs of the virus. In May 2024, the Canadian Food Inspection Agency tightened import controls on US cattle by requiring exporters to present negative avian influenza test results for lactating dairy cattle, along with mandatory testing of retail milk for virus traces. If these measures were adopted globally, this could help limit the spread of H5N1 beyond the US.3. Market Capacity for Protective Equipment: Due to the COVID-19 pandemic, access to Personal Protective Equipment (PPE) such as masks and goggles in commercial markets has significantly improved. However, even with these more diversified supply chains, the US strategic national stockpile should be prepared to provide ample protective equipment to farmers, healthcare systems, and other affected entities, particularly in rural areas far from urban centers.4. Readiness to Produce Required Vaccines: Another key preventive measure in ensuring that the current H5N1 cases do not escalate into a pandemic is ensuring capacity to produce sufficient vaccines for any H5N1 variant. The US National Vaccine Program Office stated that the federal government contracts with three manufacturers that would be capable of quickly producing bird flu vaccines in the necessary quantities using three FDA-approved platforms: egg-based flu vaccines, cell-based flu vaccines, and hybrid vaccines. This ensures that if one platform failed or if a manufacturer encountered any production issues, alternative options would be available.In conclusion, although the transmission of avian influenza to mammals, specifically cattle, has raised concerns about the potential for H5N1 to spread to humans, it is unlikely to become a global pandemic under current conditions. With no evidence of human-to-human transmission, the CDC continues to assess the risk to humans as low. Therefore, it is not projected that vaccine production will ramp up in the near future. However, if such a need arises, countries and governments will likely be in a better position to respond compared to the early days of the COVID-19 pandemic.

Understanding the New Cases of Bird Flu