The vaccine in prevention, but also as a treatment? In general, vaccines have a preventive role: they teach the body how to fight against a pathogen so that it is ready for a possible encounter with this microbe. This is the case with vaccines against Covid-19, which generate antibodies that will be able to recognize the coronavirus if it ever tries to infect the body. But a new study could expand the use of the vaccine, which in addition to preventive medicine would also become a treatment for people already infected. Because the study in question, published on May 18, 2022 in the journal BMJshows that vaccinating patients with long covid could reduce the number and intensity of their symptoms… Could the vaccine become a treatment for long covid?
Improvement after each dose of the vaccine
Researchers from the British Statistics Office (ONS for Office for National Statistics) and several universities across the Channel (Leicester, Oxford, Southampton and London School of Hygiene and Tropical Medicine) analyzed information collected in the survey on the ONS Covid-19, which has more than 320,000 participants aged 18 to 69 to date. These participants, chosen at random from across the UK, are tested for covid at every doctor’s visit, whether or not they have symptoms, which helps to capture asymptomatic infections as well and thus better estimate the true number of people infected at some point.
The researchers were more specifically interested in nearly 30,000 of these participants, who had had a confirmed infection before their vaccination and a follow-up after the infection of at least 12 weeks. Among these 30,000 participants, 6,729 (therefore 23.7%) had symptoms of long covid. And their likelihood of having long covid was stable…until vaccination. The first dose of the vaccine was associated with an approximately 13% reduction in this risk of having long covid symptoms. The second dose (which was administered on average 72 days after the first) reduced the risk even more (8.8% more). After this second dose, this risk continued to decrease by an additional 0.8% each week, at least for 12 weeks.
This reduction concerns most symptoms
This reduction was also observed for the heaviest cases of long covid. Just under 5,000 participants had a long covid that limited their daily activities. In them, a first dose of the vaccine reduced the probability of having such limiting symptoms by 12.3% and the second by an additional 9%, with a subsequent reduction of 0.5% per week. These improvements in long covid symptoms were visible regardless of the vaccine studied (RNA or viral vector such as AstraZeneca).
These reductions in long covid symptoms were visible for the majority of symptoms studied. The symptoms most improved by the first dose were loss of smell (-12.5%), loss of taste (-9.2%) and sleep disturbances (-8.8%). Whereas after the second dose it was fatigue (-9.7%), headaches (-9%) and sleep disturbances (-9%).
Vaccination could reset the immune response
The authors propose that this improvement in long covid with vaccination could be explained by a reset of the immune system: since long covid is possibly caused by a dysregulation of the immune system, the immune response induced by the vaccine could in some way so press “reset” and allow the immune system to start from scratch. Also, it could be that the vaccination helps the body get rid of any viral reservoir that could be causing the symptoms or overstimulating the immune system and thus deregulating it.
More studies are needed before considering the vaccine as a treatment for long covid
These data confirm a French study published online in preprint on September 29, 2021, where 900 long covid patients were followed. Half of these patients were vaccinated after infection, and they also showed a reduction in long covid symptoms 120 days after vaccination compared to non-vaccinated patients, as well as a decrease in the impact of the disease on the patient life.
However, vaccination may not be beneficial for all long-covid patients. According to one japanese study of 42 long-covid patients, published on March 2, 2022, symptoms improved for 17% of patients, but were instead increased after vaccination in 21% of patients. The authors propose that this difference is due to the level of antibody production. Vaccination increases the number of antibodies against the coronavirus, but this increase was four times greater in patients who saw their symptoms worsen compared to those where symptoms improved. The authors don’t know why these patients’ immune systems reacted so strongly to the vaccination. And until this problem is understood, vaccination cannot yet be used as a treatment for long covid, even if it could be recommended to avoid reinfection.
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