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Universal Vaccines Assessed for Widespread Flu Prevention

Vaccination (U.S. Army Corps of Engineers)

(U.S. Army Corps of Engineers)

Researchers In the U.S. and the U.K. have developed a simulation model to assess the ability of universal vaccines — those that cover a number of disease variations — to prevent the spread of influenza. The team from Princeton University and Duke University, Imperial College London, National Institutes of Health, and Food and Drug Administration reported their findings last week in the Proceedings of the National Academy of Sciences (paid subscription required).

Princeton biology postdoctoral researcher Nimalan Arinaminpathy and colleagues devised a computational model to measure the impact of universal vaccines on the way flu viruses spread in the population. Today’s current flu vaccines are produced to counter the influenza strains that the World Health Organization predicts will dominate a particular flu season. This reactive approach does not offer long-term or widespread immunity, since the flu virus is always evolving, thus vaccines need to be updated each year.

Current vaccines target hemagglutinin proteins on the virus’ surface that allow the virus to attach to and invade host cells. Small mutations in these appendages can create what is known as “immune escape,” where new versions of the virus are often invulnerable to the vaccine designed for their former version. Universal vaccines instead bypass the hemagglutinin surface and attack different components of the virus. As a result, the hemagglutinin proteins remain active and may cause infections, but do less damage and cause less suffering to individuals.

Arinaminpathy’s team tested the model on two sets of scenarios involving the spread of an influenza virus through mass populations. They assumed their hypothetical vaccine would not necessarily prevent infection, but rather reduce the severity of symptoms such as coughing and sneezing, which would bring down the chances of transmitting the virus.

In one of the scenarios, a flu pandemic — where a new, highly contagious strain of a virus spreads suddenly and rapidly — is difficult to control through vaccination alone. But the simulation indicated that universal vaccines deployed on a large scale could avert a pandemic, even if only a part of the population is vaccinated.

The researchers ran the model as well on scenarios involving seasonal flu epidemics that recur each year. The model suggests that universal vaccines, if maintained over several years, could slow viral evolution and the immune escape phenomenon. The simulations indicate that lowering the rates of infection through universal vaccines would also lower immunity to the dominant strain, since fewer people would contract this type of flu.

Lower rates of infection, however, would also mean that fewer people could harbor virus mutations in the first place because they never caught the original strain. “Our model illustrates how we can control the flu this way, instead of simply reacting to it every few years,” says Arinaminpathy. “We found that by putting the brakes on flu transmission, you could also put the brakes on flu evolution.”

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