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How to prevent bird flu from becoming the next pandemic

IIf H5N1 turns into a real pandemic, we are currently in the first chapter. To prevent Chapter Two from becoming a reality, the most important tool in our arsenal will be large-scale testing. Testing is not just about diagnosing people infected with the virus. Containing the spread of this highly pathogenic strain of avian influenza in cattle depends on our ability to detect and track it.

The H5N1 outbreak in dairy cows is widespread and spans several US states. Although only one human infection with the virus has been documented, other infections will likely go unnoticed. More importantly, uncontrolled transmission between cattle means the virus is increasingly colliding with humans. Each human exposure, in turn, offers the possibility of new mutations that could allow human-to-human transmission.

The US Centers for Disease Control and Prevention (CDC) says that at this time, the risk to the general public from H5N1 remains low. And indeed, it is entirely possible that H5N1 will never turn into a human pandemic.

However, getting it wrong would be extremely costly.

We find ourselves in a situation not unlike that of early 2020, when the United States was on the brink of the COVID-19 pandemic and reluctant to take decisive action, limiting testing only to people with epidemiological links with China. Scientists estimate that as of early March 2020, less than 1% of SARS-CoV-2 infections in the United States had been detected by testing. We have effectively gone through chapters one and two of the COVID-19 pandemic blind.

Today, genomic analyzes tell us that avian flu had been circulating in dairy cows for at least four months before being detected in March 2024. This delay occurred despite early warning signs of infections in dairy cows. dairy farms in February. The U.S. government cannot afford to repeat the mistakes made early in the COVID-19 pandemic. Although the risk of an H5N1 influenza pandemic is currently low, the consequences of inaction could be catastrophic, and the benefits of proactive testing far outweigh the short-term costs.

Learn more: Why experts are worried about bird flu in cows

Despite the high stakes, government action was initially slow and uncoordinated. Until mid-April, testing was not only voluntary but limited to symptomatic animals, with limits on the number of tests per farm. A complicating factor is that responsibility for controlling the outbreak is shared among three federal agencies: the U.S. Department of Agriculture (USDA) for livestock, the U.S. Food and Drug Administration (FDA) for food safety and the CDC for human health and surveillance. Yet, as of May, the CDC was aware of only about 30 people who had been tested for bird flu. The CDC has been monitoring data from emergency services in areas where the H5N1 virus has been detected in livestock and has found nothing unusual so far. But if infected people show up in the emergency room, it will be far too late to contain the epidemic at its source.

We have to stop flying blind. Regular, widespread testing is our only way to detect H5N1 and prevent the spread of the virus.

The recent federal order requiring mandatory testing of dairy cows before they cross state lines is a step in the right direction. But we could do more: we should encourage testing rather than restrict it. A tiered testing strategy combining monitoring of waste or sewage on farms, routine testing of milk from cows, and active surveillance testing of animals and humans, including those without symptoms, is our best hope of stopping the spread of the virus.

The tools and infrastructure necessary for such a testing program are already at our disposal. During the pandemic, the U.S. government has spent billions to support testing and create a vast biomonitoring infrastructure. Influenza surveillance through wastewater monitoring has already shown an increase in the H5 subtype, the viral group to which H5N1 belongs. In 2024, laboratories in the United States now have idle PCR machines, waiting to be turned back on. And U.S. test manufacturers have efficient automated manufacturing lines capable of producing millions of rapid tests per day.

Learn more: Is it safe to eat eggs and chicken during bird flu outbreak?

For animal testing, we should accelerate evaluations of laboratory and on-site testing. Testing should include cows, but also pigs, which are known to be “mixing vessels” of viruses between host species. We should also evaluate different samples like swabs and cow’s milk, including pooling samples to test more efficiently.

If existing rapid tests for influenza A could detect the virus from a drop of contaminated milk, it would be a game-changer. Given the extremely high viral load detected in the milk of infected dairy cows, it is possible that just one drop is enough. But if the tests need to be refined, the USDA and FDA should fund studies along these lines now. With H5N1 circulating in herds nationwide, we can quickly evaluate the effectiveness of these tests and refine our strategies accordingly.

Regarding human testing, it is commendable that the CDC is now engaging with test manufacturers to develop a widely available H5N1 test. In the meantime, existing authorized rapid tests for influenza A will likely detect H5N1. To confirm, the CDC, FDA, and the National Institute of Health’s Rapid Acceleration of Diagnostics (RADx) program should support assessments that address this knowledge gap. If these rapid influenza tests detect H5N1, we may send any positive influenza A test to a laboratory for confirmation and evaluation of H5N1 or another virus. This surveillance testing algorithm, which leverages broad influenza tests for initial screening and reserves more H5N1-specific tests for confirmation, followed by rapid sequencing of positives, would allow us to allocate our resources to public health with maximum efficiency. Rapid turnaround times for testing when needed would allow infected people to immediately isolate and obtain antiviral flu medications, minimizing the risk of transmission.

The federal government keeps the antiviral influenza drug Tamiflu as well as personal protective equipment (PPE) in its strategic national stockpile. To ensure that tests are also available, the government must send a clear signal to manufacturers, committing to purchasing a substantial quantity of tests, just as they do for antivirals and PPE. This would give manufacturers the confidence to increase production and create a strong national stockpile. Congress should allocate funds to support these efforts, with the new White House Office of Pandemic Preparedness and Response coordinating a unified response across the CDC, USDA and FDA.

The government must also address the stigma associated with positive test results and provide financial assistance and resources to help affected farmers and their workers. For example, many people working on dairy farms are undocumented. The current administration should provide safeguards providing protection to undocumented workers who agree to submit to testing under public health surveillance testing programs.

Prevention success in public health is difficult to track, and success in preventing a pandemic can be misinterpreted as failure or misuse of funds. It is almost impossible to recognize the absence of a pandemic that never occurs, but would occur without aggressive and early efforts. However, tracking detections and documenting actions taken will be helpful. The cost of inaction far exceeds the cost of prevention. We risk losing all the lessons learned from COVID-19 if we don’t apply them now.

The good news is that we have the tools to prevent an H5N1 pandemic. But we must be ready to use them, and quickly.