Adverse effects rare for vaccines, no need to panic over long-term impact, say experts

CHENNAI: Vaccine manufacturing behemoth AstraZeneca’s recent acknowledgement that its Covishield vaccine against SARS-CoV-2, the coronavirus variant that caused the COVID-19 pandemic, may lead to thrombosis thrombocytopenia syndrome (TTS) in rare cases, has spread panic among the thousands of people who have received multiple shots of the vaccine.

Firstly, this is not a ‘revelation’ as claimed by some, especially the anti-vaccine group, because the adverse effects of the vaccine have been considered, studied and discussed earlier itself by government bodies like the National Institutes of Health, United States, and research published in prestigious journals like the ‘Nature’.

Secondly, all vaccines have side-effects, most of them minor and temporary. The experts whom DT Next spoke to are unanimous that the advantage that vaccines offer far outweighs the mild side-effects they pose. According to the World Health Organisation’s 2024 study, 50-year impact analysis of Expanded Programme on Immunisation, vaccination has saved as many as 150 million lives globally in the last decades.

Covishield, the Oxford-AstraZeneca's COVID vaccine that was manufactured and marketed in India in partnership with Pune-based Serum Institute of India, was the shot that most people in the country have taken.

Explaining the basics, senior virologist Dr Jacob John said while a vaccine is a chemical or a noxious agent, its concentration in the body steadily declines as it is broken down by body functions. It is opposite in the case of an infection, as the load of the virus or bacteria that infects the body increases with the passage of time. The adverse effects of a vaccine are usually considered relevant from 4 to 6 weeks. There is no major impact after that.

"There is no replication of the vaccine components in the body after it is administered. So, if a person takes a vaccine [as recent as] three months ago, the adverse effects cannot hold any relevance now. There is nothing to worry about the vaccine now. People who have had an adverse impact had them within a short duration of the administration of the vaccine - some even died due to it. We don't have credible, reliable or authentic scientific data on this to come to any conclusion," he said.

The decision to allow the use of Covishield was the right one, as the risk of developing complications due to COVID was higher than the risk from the vaccine, he said, noting the profit-risk balance. In his opinion though, Covaxin was a better choice. “There should be an admission of reality, accountability and transparency in the case of people who died due to adverse effects and they should be given compensation," said Dr John.

Noting that all vaccines have certain adverse effects, experts added that linking the vaccine to an increase in the incidence of heart attacks was not appropriate.

"The vaccine helped bring down the severity of the infection in sick patients, those with comorbidities such as respiratory illnesses. The mortality was high during the second wave of the pandemic, but it reduced significantly when the third wave hit the country. The cases were high but the deaths due to the infection dipped. The vaccine was given to the majority of the population based on its efficacy," added Dr Ashok Kumar, senior consultant, interventional cardiologist at Rela Hospital.

Even as the reports about the rise in incidence of heart attack after the vaccination campaign across the country are being widely shared, Dr Kumar said there have been reports from different parts of the world about rare cases of blood clots in various parts of the body after vaccination. However, he added, this is a rare phenomenon.

"In Europe, even among the general population, there are about 1 lakh cases of blood clots in a month. This hasn't changed after the vaccination. So, we are unsure if there is an increase in such incidents mainly due to the vaccination but there is a rare possibility. The shift in lifestyle, especially with the lack of physical activity, have contributed to a large extent to the increase in heart attack," he added.

According to Dr Dhruv Chauhan, national council coordinator of the Indian Medical Association-Junior Doctors' Network, there is not a single vaccine or drug which doesn’t have any "rare side-effects". What that means is, there is a possibility that "10 in 1 lakh people" may face some rare adverse effects, while the other 9,99,990 people are safer from the disease against which they took the vaccine.

"All the vaccines that you have taken since birth, including the BCG vaccine, has the rarest possibility to cause Osteitis-arthritis. Yet, the majority of us have grown healthy and are living with its protection the whole life. When vaccines or drugs are under trial, the goal is to produce them with minimum side effects and maximum benefit for an individual to prolong their life. During the pandemic, unnecessary fear and panic killed more people than the pandemic itself," he added.