Vaccines are now an important tool to prevent acute and severe coronavirus disease (COVID-19). However, little is known about the long-term effects of the new coronavirus. Can vaccination against SARS-CoV-2 protect against long-term COVID-19, and how does vaccination affect existing long-term COVID-19 infections?
Prevention of long-term novel coronavirus infection
Because COVID-19 vaccines are effective in both preventing disease and reducing the severity of the disease, the CDC recommends vaccination to prevent long-term infection with COVID-19.
“If you don’t get COVID-19, you can’t have long-term infection with COVID-19,” Dr. Lisa Saunders, medical director of the Yale-New Haven Long COVID-19 Consultation Clinic in Connecticut, told MedPage Today. .
“Second, if you get infected with COVID-19 after getting vaccinated, you are less likely to get severe COVID-19. And the worse the infection, the longer you are likely to get COVID-19. They are more likely to get infected,” she explained.
Observational data seems to support this. A recent meta-analysis of six studies found that having received at least one dose of COVID-19 vaccine before infection was associated with about a 50% chance of developing long-term COVID-19 infection. (OR 0.539, 95% CI 0.295-0.987, P=0.045)) when compared to no vaccination.
In one study of more than 20 million participants in the UK, Spain and Estonia, the COVID-19 vaccine reduced the risk of long-term illness from COVID-19 by approximately 29-52%. A separate analysis of more than 2.3 million vaccinated Norwegians and 1.5 million unvaccinated Norwegians found that all new vaccines, including mRNA vaccines and AstraZeneca’s ChAdOx1 vaccine (not yet authorized in the United States), Taking a coronavirus vaccine reduced the risk of developing long-term COVID-19 infection by 36% (subdistribution HR 0.64, 95% CI 0.55-0.74).
CDC data presented at the 2023 IDWeek Annual Meeting suggested that mRNA vaccines are also effective in children. People who received the mRNA COVID-19 vaccine during the Omicron variant outbreak were up to 48% less likely to develop post-COVID-19 symptoms after infection. The vaccine also reduces the risk of respiratory illness after COVID-19 by 47%.
However, in contrast to these studies, a previous large observational study using data from veterans found that vaccination was less effective in reducing the risk of long-term illness from COVID-19. . The study found that vaccination reduced acute sequelae of COVID-19 infection by only 15% (HR 0.85, 95% CI 0.82-0.89) in patients with breakthrough infections.
One bright spot is that the incidence of long-term COVID-19 infections appears to be decreasing over time, largely due to vaccination, according to a recent analysis of Department of Veterans Affairs data. Among those infected after vaccination, the incidence of acute sequelae decreased from approximately 5.3% in the Delta era to 3.5% in the Omicron era. The researchers also found that about 72% of the long-term cumulative risk reduction for COVID-19 between the Omicron era and earlier eras can be attributed to vaccines, while about 28% can be attributed to changes in virus pathogenicity. They also found that this may be due to era-related influences.
Treatment of long-term coronavirus infection
How COVID-19 vaccines will improve or worsen existing long-term COVID-19 symptoms is a much more ambiguous question with few, if any, answers.
A meta-analysis of 11 studies from very early in the pandemic found evidence of improvement in long-term COVID-19 symptoms among people who received at least one dose of the vaccine after being fully vaccinated. Found some. However, some studies have found that long-term COVID-19 symptoms remain unchanged or even worsen with vaccination.
A separate analysis of studies from 2021 found that seven studies found that most people with long-term coronavirus infections did not experience a change in symptoms after receiving one or more doses of a coronavirus vaccine. .
A revealing study of more than 800 people in the UK with long-term COVID-19 infections found that around 58% of participants reported improvement in symptoms after vaccination, and 18% reported worsening of symptoms. and the rest reported no change. However, of note, there was a greater improvement in symptom severity scores in patients who received the mRNA vaccine compared to the adenoviral vector vaccine.
Even if vaccines have a positive or negative impact on long-term coronavirus symptoms, there’s no definitive answer as to why or whether it’s a placebo effect, says the University of California, Los Angeles, infectious disease expert. said Otto Yang, MD, David Geffen. the School of Medicine told MedPage Today.
“Some people believe that at least some people who have had COVID-19 for a long time actually continue to replicate the virus, so vaccination and a strengthened immune response can help. “We can hypothesize that that could be mitigated.”
“On the other hand, some people who have been infected with the new coronavirus for a long time may be suffering from some kind of autoimmune disease caused by the new coronavirus, and vaccination may increase their immune response and worsen the situation. “I can imagine that it could happen,” he hypothesized.
“You can wave your hands any way you want and come up with any mechanism you want. We’re really in the dark about that at the moment. And both of those things could be true. , or there’s a good chance that neither of them is true.” Some of them are true,” he stressed.
get a better answer
Current research on the effectiveness of vaccines against the coronavirus over the long term is entirely observational. There are no randomized controlled trials on this topic, and there probably never will be, for several reasons, Yang told MedPage Today.
The first problem with vaccine and long-term coronavirus research is that there is no agreed-upon definition of long-term coronavirus, and there are no objective measures of disease such as laboratory tests, biomarkers, or imaging. “What we call long-term coronavirus is probably a conglomeration of different types of processes,” Yang said. “Without a clear definition of the condition, research becomes very difficult.”
Additionally, the ability to study the effects of vaccines against COVID-19 over the long term is further complicated by the fact that the majority of people have received multiple doses of the vaccine or have been infected with COVID-19. “It’s going to be very difficult,” Yang commented. “We don’t have a blank slate, so to speak, in terms of studying this, because people are going to be very diverse in terms of how much exposure they’ve had in the past.”
Dr. Saunders recommends that patients get vaccinated against the coronavirus to reduce the risk of post-acute complications. “I’m not afraid of the coronavirus, but I’m pretty worried about how long it will last,” she said.
“Every time you get infected with coronavirus, you carry the same risks,” she commented. “I’ve had patients who’ve had COVID six, seven, eight times, and now they finally have long-term COVID… It’s a shitty shoot every time.”
Katherine Kahn is a staff writer for MedPage Today, covering the infectious disease beat. She has been a medical writer for over 15 years.
disclosure
Mr. Sanders reported no relevant conflicts of interest.
Mr. Yang reported that he serves as a consultant for CytoDyn.
