A nurse administers a booster shot at a Covid-19 vaccination clinic on April 06, 2022 in San Rafael, California.
Justin Sullivan | Getty Images
The Covid vaccines, while holding strong against hospitalization and death, offer little protection against long-term Covid, according to the study published Wednesday in the journal Nature Medicine.
The results are disappointing, if not surprising, for researchers who once hoped vaccination could significantly reduce the risk of long-lasting Covid illness.
Compared to an unvaccinated person, the risk of a long covid in a fully vaccinated person was reduced by only about 15 percent, the study found.
“The vaccines miraculously do what they were designed to do” — that is, prevent hospitalization and death, said Dr. Ziyad Al-Aly, clinical epidemiologist at Washington University in St. Louis and lead author of the study. But they “offer very modest protection against long Covid,” he said.
The Covid vaccines were developed early in the pandemic, long before doctors, scientists and patients knew of the existence of the long Covid. They were never designed to protect against them, said Al-Aly, who is also a research director at the VA St. Louis Health Care System. “We have to reconsider them now that we know that the virus can also have long-term consequences.”
dr Greg Vanichkachorn, director of the Mayo Clinic’s Covid Activity Rehabilitation Program in Rochester, Minnesota, who wasn’t involved in the new study, said the results weren’t “too surprising”.
“We know that the majority of people with long Covid have not had serious infections,” he said.
The study looked at national health data from the US Department of Veterans Affairs and included medical records of nearly 34,000 vaccinated people who had breakthrough Covid infections from January 2021 to October 2021 and more than 113,000 who were unvaccinated when they contracted Covid. Individuals were considered fully vaccinated if they had received two doses of Pfizer-BioNTech or Moderna vaccine or a single dose of Johnson & Johnson vaccine.
The researchers followed six months after infection to see if the patients had ongoing symptoms. While protection from long Covid was generally relatively low, vaccines were more effective at preventing some of the most life-threatening long Covid symptoms: Vaccination reduced the risk of lung disease by almost 50 percent and 56 percent of blood clotting disorders compared with those who were not vaccinated.
Al-Aly noted that one breakthrough case doesn’t mean a person will long develop Covid – only about 10 percent of breakthrough cases result in the disease – but with so many infected, that still means a large number of people.
The data didn’t show whether a person was boosted, but Al-Aly said he doesn’t expect the boost to make much of a difference in terms of long-Covid protection vaccines or variants like Omicron.
Vanichkachorn agreed. “Unfortunately, I don’t think the booster will do much to prevent Covid with the vaccine for long,” he said. “We have many patients with breakthrough infections who are vaccinated as best they can. We also didn’t see much of a difference between variants with long Covid symptoms.”
That’s not to say vaccines aren’t an important tool in the fight against the pandemic, experts say.
In particular, booster shots offer the greatest 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 think vaccination is the key to eliminating Long Covid,” Al-Aly said. “We really need to think about additional layers to protect against the long-term consequences of this virus.”
New approaches to prevent long covid
Covid cases are rising again in the US, now driven by an Omicron subvariant called BA.2.12.1, according to the Centers for Disease Control and Prevention. Despite this, public health measures such as masking and social distancing have largely fallen away.
Al-Aly said he doesn’t blame people.
“It’s not pragmatic to tell people to mask themselves for the next 10 years,” he said. But it underscores the need to improve vaccines and treatments so they could offer protection from long-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. “This makes the question of what other prevention or treatment options might be available even more pressing. Can we optimize these original vaccines to also treat long Covid, or do we also need intranasal vaccines or other therapies as well?”
Intranasal vaccines, for example, might be better at preventing transmission than current vaccines, but this is an area that needs investigation, he said.
Maley, who was also not involved in the study, said increasing research suggests one of the main risk factors for long Covid is virus levels in the body during acute infection. This suggests that early treatment with therapies, including antiviral drugs, can help prevent a long covid by keeping these viral levels down.
“Right now, antivirals are approved for emergency admissions for patients who are at high risk for severe Covid-19, typically older adults or those with compromised immune systems,” Maley said. There is also an interest in investigating whether antiviral treatments could benefit long Covid patients.
Both Al-Aly and Vanichkachorn agreed that more research on Long Covid is needed. “We need continued research specifically on long Covid so that specific therapies can be developed,” Vanichkachorn said.
But right now, he said, “the best way not to get Covid for long is not to get Covid.”