Flu shot won't make you spread more influenza

Getting the flu shot won't make you spread the disease more, doesn't weaken your immune system but it does offer some protection from getting infected, despite misleading claims on social media.

A post on a site called thewilddoc claimed that being vaccinated does more harm than good, citing a January peer-reviewed study. But one of the main authors of that study called the post "untrue" and "misleading," not accurately interpreting the study.

In January, Dr. Donald Milton and a team of researchers at the University of Maryland published a study in the journal Proceedings of the National Academy of Sciences about how the influenza virus spreads not just in coughs, but also in the breath of 142 flu-struck people. Of those people with flu, only 22 percent had gotten vaccinated that year, but among those who had been vaccinated they shed six times more tiny aerosols of the flu.

The social media post than took that study and made four claims, all of which Milton said were untrue or misleading.

The biggest claim from the posting—"individuals who receive the flu vaccine are placing others around them at greater risk than the unvaccinated"—is wrong, according to Milton, who has a medical degree and doctorate in public health. "Unvaccinated people are more likely to get the flu and transmit it to other people because they shed lots of virus into the nasal secretions into the air," he wrote in an email.

Milton said people who are sick with flu shed about 40,000 viruses or so every half hour. While sick people vaccinated shed six times more aerosols than the sick who weren't vaccinated, that's not the proper way to look at it, Milton said. People who are not sick because they got vaccinated don't shed and spread flu, which is a more meaningful comparison, he said.

Further, Milton said the part about more virus shed by those vaccinated "is based on only 11 cases" so that makes it preliminary and needs to be confirmed, something that prominent flu researcher Peter Palese, chairman of microbiology at the Mt. Sinai Medical School in New York City, agreed with. Palese edited the Milton study for the scientific journal.

The posting also claimed Milton's study shows that "the vaccine doesn't protect one from infection." Milton, in an email, called this wrong and said his study didn't examine vaccine effectiveness. His research just looked at sick people, most of whom had not gotten shots, he said.

The post claimed that Milton's study showed that people who had been vaccinated are spreading more virus simply by breathing. Milton called that misleading because all flu-struck people spread the disease simply by breathing, even more if they cough.

And the post also claimed that Milton's study shows that getting vaccinated weakened immune systems. Milton said that people who are vaccinated are not more likely to get sick than others, and even when the vaccine didn't protect patients from illness, it did not affect the immune system.

Palese said the social media post is a classic example of "shoddy scholarship and should best be ignored."

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