As the pandemic enters its third year, protracted Covid is becoming more of a problem. And many people wonder if getting a Covid shot can reduce the chance of developing long-term symptoms.
What do the studies show so far?
The jury is still pending, but a growing body of research suggests that Covid vaccination can reduce, though not eliminate, the risk of long-term symptoms.
The United Kingdom Health Safety Agency conducted analysis of eight studies published on this topic up to mid-January. It reports that six studies have shown that vaccinated people who contract the coronavirus are less likely than unvaccinated patients to develop symptoms of long-term Covid. The two remaining studies have shown that vaccination does not appear to reduce the likelihood of developing prolonged Covid-19.
What kind of protection can vaccines offer, according to studies that have shown benefit?
Some research results suggest significant protection, while others show little benefit.
One great study Electronic patient records at the US Veterans Health Administration found that vaccinated Covid patients were only 13 percent less likely to develop symptoms after six months than unvaccinated patients.
Two studies in the UK found a larger effect. One study about 1.2 million people, based on patient reports via a phone app, found that the risk of lingering symptoms among vaccinated patients was 50 percent lower. Anotherwhich was not peer-reviewed and was based on a survey of about 6,000 patients, found a 41 percent risk reduction.
BUT study of patients in the US Arcadia, a health data company, and the Covid Patient Recovery Alliance, a collaboration of leaders with government and private sector health backgrounds, have found even greater benefits. The study, which has not been peer-reviewed, analyzed records of approximately 240,000 patients infected with coronavirus by May 2021 and found that those who received at least one dose of the Covid vaccine prior to infection were one-seventh to one-tenth chance of reporting two or more symptoms of long-term Covid after 12 to 20 weeks. This study also found that people who received the first dose of the vaccine after contracting coronavirus were less likely to develop long-term Covid than those who remained unvaccinated, and the earlier they were vaccinated after infection, the lower the risk of long-term symptoms.
BUT study in Israel, which was also not peer-reviewed, interviews found that people who received two doses of the vaccine had a 54-82% lower risk of reporting seven of the 10 most common long-term symptoms than unvaccinated patients. The study says they tended to be no more likely to report symptoms such as headache, muscle pain and other problems than people in general who had never had Covid. (The authors said they could not confirm whether patients were vaccinated before or after they contracted Covid, but said that due to Israeli vaccination policy, it is likely that most people who received two doses of the vaccine contracted the coronavirus some time after how they got infected. their shots.)
in veterans’ office, also not yet published in a peer-reviewed publication, the researchers compared about 48,000 patients who were not vaccinated when they got Covid with about 16,000 patients who were vaccinated. According to one of the authors, Dr. Ziyad Al-Ali, head of research and development at the Virginia Health System in St. Louis and a clinical epidemiologist at Washington University in St. Louis. Other symptoms showed “very little reduction in risk” from the vaccines, he said.
“The general idea is that vaccines reduce but do not eliminate the risk of long-term Covid,” said Dr Al-Ali, adding that “relying on vaccination as the only mitigation strategy is completely inadequate. It’s like fighting with a shield that only partially works.”
What about studies that show no benefit?
AT analysis electronic health records of patients in the United States, researchers in the United Kingdom compared about 10,000 people who received Covid vaccines with the same number of people who were not vaccinated against the coronavirus but received the flu vaccine – an attempt to limit the number of people in the study who could be considered hesitant about vaccination or who generally led a less healthy lifestyle.
A study found that having a coronavirus vaccine before exposure does not reduce the risk of most symptoms of long-term Covid. The authors wrote that the data suggested that vaccinated people may have a lower risk of long-term symptoms such as abnormal breathing and cognitive problems, but these results were not statistically conclusive.
The researchers said that perhaps because their data was based on electronic health records, the study could only have included patients with the most severe symptoms, rather than a wider range of patients who did not seek medical attention for their symptoms.
Why are the studies conflicting?
One reason is the differences in the studies themselves. Not all researchers defined long-term Covid in the same way, measured the same symptoms, or tracked patients over the same period of time. For example, some studies recorded symptoms that persisted for at least 28 days after exposure, while others measured the symptoms people experienced after six months. Surveys based on patient surveys can produce very different results than those based on electronic health records. And some studies didn’t have very different populations. For example, patients in the Veterans Study were mostly elderly, white, and male.
Are the results different for different coronavirus variants?
Most of the data published has been for patients infected early in the pandemic. Some recently published data included people infected with the highly contagious Delta variant, but it is still too early for research on vaccines and long Covid that includes the Omicron variant. It is also too early to conduct studies evaluating the impact of boosters on long-term Covid.
Is there anything scientists can conclude for sure?
Yes. Vaccines are very effective in preventing people from becoming seriously ill with all the options known so far. And many studies have shown that Covid patients sick enough to be hospitalized are more likely to have long-term health problems. So by keeping people out of the hospital, vaccines should reduce the chance of such a long-term post-COVID case.
However, many people with long-term Covid have had mild or even asymptomatic initial infections, and while some research suggests that vaccines can improve their long-term symptoms, the evidence is not yet conclusive.
Vaccines do provide some protection against infection right from the start – and preventing infection is, of course, the surest way to prevent lingering Covid.
Does vaccine brand affect potential protection against long-term Covid?
So far, studies have not found that different vaccines have different effects on long-term symptoms.
What are the possible scientific reasons that vaccines can protect against long-term Covid?
Scientists say the cause of prolonged Covid is still unclear, and different symptoms may have different causes in different patients. Some believe that this condition may be due to remnants of the virus or its genetic material remaining after the initial infection clears up. Another theory is that the ongoing problems are due to inflammation or circulatory problems caused by an overactive immune response that cannot shut down.
Akiko Iwasaki, an immunologist at Yale University, said vaccines could provide long-term relief for people whose symptoms are caused by remnants of the virus if the antibodies produced by the vaccines destroy those remnants.
But in people whose symptoms may be due to a post-viral reaction that resembles an autoimmune disease, she said, vaccines can only help temporarily, and problems like fatigue can reappear.
Can vaccination help if you have had Covid for a long time?
When vaccines were first introduced, some long-term Covid patients found that symptoms such as brain fog, joint pain, shortness of breath and fatigue improved after vaccination. However, many people did not feel any change in their symptoms after being vaccinated, and a small percentage said they felt worse.
Research conducted Office for National Statistics in the United Kingdom found that in people aged 18 to 69 who reported their symptoms between February and September 2021, the first dose of the vaccine reduced the likelihood of reporting long-term Covid symptoms by 13 percent. The study found that the second dose further reduced the odds by 9 percent.
Recent analysis The UK Health Safety Agency evaluated this study and seven others that looked at whether vaccinating people with long-term Covid affects their symptoms. It found that in most of these studies, more people with long-term Covid reported an improvement in their symptoms at some point after vaccination. However, some people also reported worsening symptoms, and in several studies, most people stated that their symptoms had not changed.
The agency noted that the definition of long-term Covid varies greatly between studies and that because all studies were observational, changes in symptoms could be due to factors other than vaccination.