BackHigh immune response to Covid variants in breakthrough cases after 2 Covaxin jabs: ICMR study
A recent ICMR study says a booster dose of Covaxin provides better protection against the disease as a precaution dose significantly increases the immune response against coronavirus' variants of concern — Beta, Delta and Omicron
PremiumA recent ICMR study says a booster dose of Covaxin provides better protection against the disease as a precaution dose significantly increases the immune response against coronavirus' variants of concern — Beta, Delta and Omicron.
The study found that individuals who recovered from Covid also showed significant immunity boost post-vaccination with Covaxin but lower than the breakthrough cases. However, those who had taken two doses of Covaxin had very low neutralizing titres demonstrating the waning immunity after three months of the second dose of Covaxin.
The findings of the study, conducted in February this year were published in the Journal of Infection on April 5.
"The impact of the third wave of the pandemic in India, caused by Omicron, triggered us to study the effectiveness of Covaxin against this variant, Dr Pragya Yadav, a senior scientist at NIV Pune said.
"We assessed the sera of naïve, recovered and breakthrough cases vaccinated with Covaxin for its neutralising ability against Omicron and other variants," Dr Yadav said.
Dr Pragya Yadav said the participants were categorised into three groups — The first group was of 52 COVID-19 volunteers vaccinated with 2 doses of Covaxin with an average age of 41.7 years, the second group was of 31 COVID-19 volunteers recovered cases vaccinated with 2 doses of Covaxin with average age of 41.7 years and the third group was of 40 of breakthrough cases after two-dose vaccination with Covaxin with an average age of 43.7 years.
The sera samples of naïve, recovered and breakthrough cases, were collected on average 97, 99 and 110 days, respectively. The breakthrough infection was found to occur on average 43 days after the second vaccination.
A majority of the breakthrough cases had mild disease (95%) and two were asymptomatic, while 32.5% had co-morbidities like diabetes, hypothyroidism, hypertension, cardiac arrhythmias and allergic asthma.
"Breakthrough cases had the highest neutralising activity against all variants demonstrating a significant increase in the immune response post-infection. Recovered cases also showed significant immunity boost post-vaccination, but were lower than breakthrough cases.
"Apparently, the naïve cases had very low neutralizing titres against all the variants compared to the recovered and breakthrough cases," Dr Yadav stated.
Dr Yadav noted that Omicron was less effectively neutralized with the sera of naïve cases (12.9 fold) than recovered (7.98 fold) and breakthrough (8.84 fold) compared to B.1.
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