BENGALURU: Despite the differences in percentage, all vaccines are efficacious against Covid and any vaccine is better than no vaccine, doctors have advised. They said people must take what is easily available to them.
Various studies in India say that Covaxin is better than Covishield though their efficacy is similar. However, these studies are limited. If anybody is traveling abroad, it is better for them to take Covishield which is approved by several other countries, said Dr. Subrata Das, Senior Consultant, Internal Medicine & Diabetology, Sakra World Hospital.
"They all act in different modalities with the end goal of triggering immunity. They could be composed of a part of the virus, the whole inactivated virus, RNA of the virus, etc.
Storing the Pfizer vaccine will be hard in India as it has to be maintained at a temperature of -15 degrees to -18 degrees celsius. Russian studies show over 90% efficacy for the Sputnik vaccine," Dr. Das said, adding that if one has a history of thrombosis (blood clots), stroke, heart attack, etc, they must take a non-Covishield vaccine.
There is no need to check the antibody levels post-taking the vaccine as some vaccines evoke T-cell immunity (long-term memory of the immune response). Studies against variants are limited, even though companies claim effectiveness against them. We still do not have real-world data on this and need more time, Dr. Das explained.
"On the ground, there is no major difference in efficacy. If we are looking at a reduction in the severity of the disease, mortality, and hospitalization, the vaccine is effective after taking both doses. Incidence of respiratory issues such as low oxygen is visible even after the person takes one dose," said Dr. Anoop Amarnath, Head, Scientific Board and Chairman-Geriatric Medicine, Manipal Hospital and member of the state's Critical Care Support Team
The trials for these vaccines happened in the first and second waves. Hence, their effectiveness against variants are yet to be studied. There is not much data and the Covid vaccine may be similar to the Influenza vaccine, in the sense that the composition might change as per the prevalence of the strain, Dr. Amarnath added.
"Primary efficacy data in both Covaxin and Covishield show that they prevent moderate to severe disease with a rate of 65 percent to 80 percent. How much they diminish over time has not been studied yet. Sputnik has reported 85 percent to 90 percent efficacy, while Moderna and Pfizer have reported over 90 percent, with the percentage lowering between 40 percent to 70 percent due to diminishing," said Dr. Ravindra Mehta, Senior Consultant, and HoD, Pulmonology and Interventional Pulmonology, Apollo Speciality Hospital.