During the severe influenza season of 2017–2018, the flu vaccine was just 38% effective.Credit: Justin Sullivan/Getty

The US government is launching a programme to modernize the development of flu vaccines. President Donald Trump signed an executive order on 19 September directing the Department of Health and Human Services and the Department of Defense to propose a plan and budget for the effort within 120 days.

The goal is to improve the country’s ability to prepare for a future outbreak of pandemic flu, and to develop better vaccines to protect against seasonal outbreaks.

The programme will support research to develop a universal flu vaccine to replace the seasonal vaccine developed each year. The government also plans to create a strategy for switching to faster methods of producing seasonal flu vaccines, a senior administration official told reporters on 19 September. Currently, manufacturers produce most flu vaccines using chicken eggs, a process that takes at least six months.

Influenza viruses mutate constantly, so the strains that circulate differ from year to year. This means that vaccines must be tailor-made for each flu season. But over the past decade, flu vaccines have only been about 45% effective. That’s partly because the slow process of producing vaccines in eggs creates a months-long lag between when researchers predict which strains are likely to circulate during flu season and when vaccines reach the public. In years with especially bad mismatches between a vaccine and the virus, the effectiveness of a flu vaccine can drop to less than 20%.

Better and faster

Two faster production methods exist, both of which have been used to make vaccines that are approved by the US Food and Drug Administration (FDA). But those vaccines are more expensive than the ones made using chicken eggs.

One of the faster techniques, which uses cell cultures, can also produce more effective vaccines than do egg-based approaches, according to the FDA. The agency estimated that during the 2017–2018 season, one cell-based vaccine protected about 20% more people than did vaccines made using conventional methods. Another study1 found that the cell-based vaccine protected 10% more people age 65 or older compared with egg-based ones. Cell-based vaccines account for 10–15% of the US flu vaccine market.

The second method uses recombinant technology, and involves inserting influenza virus genes into insect cells. The cells then churn out a vaccine, which workers harvest and purify. This technique can produce vaccines within six to eight weeks and accounts for about 1–2% of the market.

A highly effective seasonal flu vaccine, produced rapidly at the start of an influenza pandemic, would save the United States an estimated US$953 billion by preventing deaths and hospitalizations, according to the White House Council of Economic Advisers.

The timing of vaccine production would be less of a concern if researchers could develop a universal influenza vaccine that protects against many strains of the virus, said another senior administration official. This would also eliminate the need to predict which strains will circulate every year.