Vaccines offer little protection against long-term Covid, study finds

A nurse administers a booster injection at a Covid-19 vaccination clinic on April 0=6, 2022 in San Rafael, California.

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The Covid vaccines, while highly resistant to hospitalization and death, offer little protection against long-term Covid, according to research published Wednesday in the journal Nature Medicine.

The findings are disappointing, if not surprising, to researchers who once hoped that vaccination could significantly reduce the risk of long-term Covid.

Compared to an unvaccinated person, the risk of long-term Covid in a fully vaccinated person was reduced by only about 15 percent, the study found.

“The vaccines are wonderful at doing what they were designed for” — that is, preventing hospitalization and death, said Dr. Ziyad Al-Aly, a clinical epidemiologist at Washington University in St. Louis and the study’s lead author. But they “provide very modest protection against long-term Covid,” he said.

The Covid vaccines were developed early in the pandemic, long before doctors, scientists and patients knew of Covid’s existence. They were never designed to protect against it, said Al-Aly, who is also chief of research at the VA St. Louis Health Care System. “We need to rethink them now that we know that the virus could also have long-term consequences.”

dr. Greg Vanichkachorn, director of the Covid Activity Rehabilitation Program at the Mayo Clinic in Rochester, Minnesota, who was not involved in the new study, said the results weren’t too surprising.

“We know that the majority of people with long-term Covid have not had serious infections,” he said.

The study looked at national health care data from the U.S. Department of Veterans Affairs and included medical records of nearly 34,000 vaccinated people with breakthrough Covid infections and more than 113,000 who were not vaccinated when infected with Covid from January 2021 to October 2021. were considered fully vaccinated if they had received two doses of the Pfizer-BioNTech or Moderna vaccine or a single dose of the Johnson & Johnson vaccine.

The researchers followed up six months after infection to see if patients had any lingering symptoms. While protection against long-term Covid was relatively small overall, vaccines were more effective at preventing some of the most life-threatening long-term Covid symptoms: Vaccination reduced the risk of lung disease by nearly 50 percent and blood clotting disorders by 56 percent, compared with those who have not been vaccinated.

Al-Aly noted that a breakthrough case doesn’t mean a person will develop Covid for long — only about 10 percent of breakthrough cases will result in the condition — but with so many people infected, this still translates to a large number of people.

The data didn’t show whether a person got a boost, but Al-Aly said he doesn’t expect boosting to make a big difference in terms of vaccines that protect against long-term Covid, nor variants like omicron.

Vanichkachor agreed. “Unfortunately, I don’t think boosting will do much to prevent long-term Covid with the vaccine,” he said. “We have many patients with breakthrough infections who have been vaccinated as well as possible. Also, we have not seen much difference between variants with long-lasting Covid symptoms.”

This is not to say that vaccines are not an important tool in the fight against the pandemic, experts say.

Boosters, in particular, offer the most protection against severe acute Covid and reduce the risk of complications, said Dr. Jason Maley, director of the Critical Illness and COVID-19 Survivorship Program at Beth Israel Deaconess Medical Center in Boston.

But for long Covid they are not necessarily the solution. “I don’t believe vaccination is the key to eliminating long-term Covid,” Al-Aly said. “We really need to think about additional layers to protect us from the long-term consequences of this virus.”

New approaches to prevent long Covid

Covid cases are on the rise again in the US, now driven by an ommicron subvariant called BA.2.12.1, according to the Centers for Disease Control and Prevention. Yet public health measures such as masking and social distancing have largely disappeared.

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Al-Aly said he doesn’t blame people for that.

“It’s not pragmatic to tell people to mask themselves for the next ten years,” he said. But it does underscore the need to improve vaccines and treatments in a way that could protect against long-term Covid.

“Now that we’ve lifted all these other public health measures, vaccines are really the only layer of protection we have,” Al-Aly said. “That puts even more urgency on what other prevention or treatments might be available. Can we adapt those original vaccines to address long-term Covid as well, or do we need intranasal vaccines or other therapies in addition?”

For example, intranasal vaccines could potentially be better at preventing transmission than current vaccines, but this is one area that needs to be explored, he said.

Maley, who was also not involved in the study, said increasing research suggests that one of the main risk factors for long-term Covid is the level of virus in the body during the acute infection. This suggests that early treatment with therapies, including antivirals, may help prevent long-term Covid by keeping those virus levels low.

“At present, antivirals are approved for emergency use for patients at high risk for severe Covid-19, usually older adults or those with compromised immune systems,” Maley said. There is also interest, he said, in exploring whether antiviral treatments could benefit long-term Covid patients.

Both Al-Aly and Vanichkachor agreed that more research is needed into long-term Covid. “We need further research, specifically on long-term Covid, so that specific therapies can be developed,” said Vanichkachor.

But right now, he said, “the best way not to get Covid for a long time is not to get Covid.”

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