On 16 Jan 2021 India began one of the biggest COVID-19 immunization drive with two vaccines, Oxford–AstraZeneca ChAdOx1 nCoV-19 (a chimpanzee adenoviral vector vaccine manufactured by Serum Institute of India; Covishield) and BBV152 (a whole-virion inactivated vaccine manufactured by Bharat Biotech; Covaxin).
Initially, only healthcare workers and front-line workers (e.g, police, paramilitary forces, sanitation workers, and disaster management volunteers) were eligible for vaccination.; Later it was extended to Indian citizens older than 60 years or aged 45–60 years with comorbidities, and then to all residents older than 45 years on 1 April 2021. Currently, vaccination is being offered to all adults aged 18 years or older in India in the national COVID-19 vaccination drive
What is Covaxin?
It is a whole inactive virus with a core of RNA and a capsid. It is India’s first indigenous COVID-19 vaccine produced by Bharat Biotech in collaboration with the Indian Council of Medical Research (ICMR) — National Institute of Virology (NIV). Furthermore, it contains a dead virus, incapable of infecting people but still able to instruct the immune system to defend against infection.
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It is a 2-dose vaccination regimen given 28 days apart. The vaccine received DCGI approval for Phase I & II Human Clinical Trials in July 2020.
According to Bharat biotech data, the vaccine received DCGI approval for Phase I & II Human Clinical Trials in July 2020, but Lacent’s case study tells something else.
The vaccine was added by WHO to its list of ‘VACCINES FOR EMERGENCY USE’ last month. It is now accepted worldwide by countries such as the United Kingdom, Canada etc.
According to manufacturer’s data, the efficacy of the vaccine was said to be:
- Against COVID-19 of any severity, 14 or more days post-dose 2, was 78%. Vaccine efficacy against severe disease is 93%.
- In adults aged less than 60 years, efficacy was 79%; and in those aged 60 years and over it was 68%.
How was the study conducted?
A case-control study among 2,714 employees of the All India Institute of Medical Sciences (a tertiary care hospital in New Delhi, India) was done. They had symptoms symbolic of COVID-19 and had an RT-PCR test for SARS-CoV-2 during the peak of the second wave when the delta variant was dominant between April 15 and May 15, 2021, in India. Cases (test-positives) and controls (test-negative) were matched (1:1) based on age and gender and then compared with occupational exposure to Covid-19, previous SARS-CoV-2 infection, and infection dates. 1068 matched case-control pairs were available for analysis.
What were the findings of the study?
- After two doses administered at least 14 days before testing, the efficacy of the vaccine against the virus was 50%.
- The effectiveness of two doses administered at least 28 days before testing was 46%
- When the doses were administered at least 42 days before testing, the efficacy was 57% (21–76)
The study does not estimate the vaccine effectiveness against hospitalization, severe disease, and death
Also, the study was not designed to estimate if vaccine effectiveness changed over time, the researchers added.
Conclusion of the study:
The study shows the effectiveness of the inactive virus vaccine, Covaxin’s efficacy against the immune evasive delta variant when there was a surge of the second wave in India. The findings support the rollout of vaccines but also make us realize that other non-pharmacological measures are also essential, such as masks, sanitisers, proper hygiene.
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