New Delhi: A study conducted by the Indian Council of Medical Research (ICMR) and National Institute of Virology (NIV), Pune, has found that Covid-19-recovered individuals with both doses of Covishield have higher immunity against the Delta variant. The study titled 'Neutralization Of Delta Variant With Sera of Covishield Vaccines And Covid-19 Recovered Vaccinated Individuals' have assessed the neutralising antibody (NAb) response of individuals immunised with Covishield vaccine (first dose and second dose), COVID-19 recovered individuals who were vaccinated (first dose and second dose) and breakthrough infections (due to Kappa and the Delta variant).
Delta variant has further mutated to Delta plus also known as AY.1.
It read, "The breakthrough cases and the Covid-recovered individuals with one or two doses of Covishield vaccine had relatively higher neutralizing responses against the Delta variant in comparison to the participants who were administered either one or two doses of Covishield." Moreover, the study suggests that there should be tracking of 'immune escape mutants'.
A comparative assessment of Covishield vaccinated individuals' (n=116) sera in different categories was performed against prototype strain B.1 (D614G) and Delta variant. Sera, under this study, were grouped into five categories: I. One dose (n=31), II. Two doses (n=31), III. COVID-19 recovered plus one dose (n=15), IV. COVID-19 recovered plus two doses (n=19) and V. Breakthrough COVID-19 cases (n=20).
All the sera were collected from the participants of the first four categories four weeks after vaccination. For the participants under the "breakthrough COVID-19 cases" category, the sera were collected two weeks after inoculating both doses, the study observes.
Currently, the vaccine appears to induce robust hormonal and cellular immune response against the SARS-CoV 2 spike protein.
The earlier investigations demonstrated a reduction in NAb titers in the sera of Covishield vaccinees against Kappa variant.
The study has found that it significantly lowers NAb titers for the Delta relative to B.1 variant.
However, it added that NAbs in breakthrough participants and the COVID-19 recovered individuals, who administered single or both doses, had relatively higher protection against Delta in comparison with individuals who took one or two-dose of Covishield.
Titer is a test that measures the presence and amount of antibodies in the blood. Through titer test the presence and amount of antibodies in the blood is measured.
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