The Claim: Nasal-Spray Flu Vaccine Can Make You Sick

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The Claim: Nasal-Spray Flu Vaccine Can Make You Sick

By ANAHAD O’CONNOR

Published: November 17, 2008

THE FACTS

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Leif Parsons

Every year, myths about the flu vaccine spread as widely as the flu itself.

Most people seem to know that the flu shot, which uses killed viruses,

cannot cause symptoms. But its newer counterpart, the nasal spray FluMist,

is slightly different. It uses live but weakened viruses, which can still

replicate for as long as three weeks.

But that alone is not enough to cause sickness or result in passing the

virus to others. In a report published in January, researchers at the Mayo

Clinic noted that the amount of virus shed by people vaccinated with the

spray is below what is needed to infect an adult. Children are slightly more

susceptible. (One researcher was listed as a consultant for MedImmune, which

makes FluMist.)

But in several studies of transmission rates, there was only one case in

which a vaccinated child passed on the virus. It occurred in a day care

center with 200 children, most 3 or younger. The child who contracted the

virus from someone else showed no signs or symptoms of flu, apparently

because the virus remained weakened and was capable of only limited

replication. Over all, studies suggest, the odds of transmitting the virus

after receiving the nasal spray are about 2.5 percent.

THE BOTTOM LINE

The flu nasal spray is most unlikely to lead to flu.

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