Thread by @PIBMumbai

Dr. N K Arora, Chairman of India's #COVID19 Working Group of the National Technical Advisory Group on Immunisation (NTAGI) speaks to @DDNewslive on India's COVID-19 Vaccination Drive, stay tuned for LIVE updates (1/n)🧵

India has currently 2 vaccines-COVISHIELD & COVAXIN. The interval between 2 doses of COVAXIN is 4 wks & consistent studies have shown that this is the right interval: Dr. Arora, Chairman, NTAGI explains why we decided to expand gap between 2 #COVISHIELD doses to 12-16 wks
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Initial studies on #COVISHIELD were very heterogeneous. Some countries like UK went for 12 wks dose interval when they introduced the vaccine.While we were privy to this data, when we decided our interval, we went for 4 wks interval based on our bridging trial data:Dr Arora
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The bridging data showed good immune response: Dr. N.K. Arora, Chairperson, NTAGI

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https://twitter.com/PIBMumbai/status/1404836779828465666?s=20

Later we came across additional scientific and laboratory data, based on which after 6 weeks or so, we felt we should increase interval from 4 wks to 8 wks, since studies showed that vaccine efficacy is about 57% when it is 4 wks and about 60% when it is 8 wks: Dr. Arora

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At that time, we discussed why we don't increase it to 12 wks, but we decided we should wait for ground-level data from UK (the other biggest user of Astra Zeneca vaccine): Dr. Arora

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https://twitter.com/PIBMumbai/status/1404837973128933381?s=20

In April's last week, Public Health England data showed that when interval is 12 weeks, vaccine efficacy was varying between 65-88% - on the basis of which they overcame their epidemic outbreak due to Alpha variant: Dr. N.K. Arora

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UK was able to come out of it because the interval they kept was 12 weeks: Dr. N.K.Arora, Chairperson, NTAGI

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https://twitter.com/PIBMumbai/status/1404839694915956738?s=20

We also thought that this is a good idea, since there are fundamental scientific reasons to show that when interval is increased, adeno-vector vaccines give better response; hence the decision was taken on May 13, to increase interval to 12-16 wks: Dr. Arora
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We have a very open, transparent system where decisions are taken on scientific basis. The COVID Working Grp took that decision, with no dissenting voice; issue was then discussed threadbare at NTAGI meeting, with no dissenting notes: Dr. N.K. Arora

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NTAGI's recommendation was that the vaccine interval has to be 12 - 16 weeks

This also gives flexibility to community, since everyone cannot come at precisely 12 weeks or so

: Dr. Arora, Chairperson, NTAGI

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https://twitter.com/PIBMumbai/status/1404841152243585027?s=20

There were other examples like Canada, Sri Lanka and 2-3 other countries which are using 12 - 16 weeks interval for Astra Zeneca vaccine which is the same as COVISHIELD vaccine: Dr. Arora, Chairperson, NTAGI

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2-3 days after we took this decision, there were reports from UK that single dose of AstraZeneca vaccine gives only 33% protection and 2 doses give about 60% protection; discussion has been going on since mid-May whether India should revert to 4 or 8 weeks: Dr. N.K Arora
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Around the same time, we were privy to several studies & it was also decided when NTAGI took this decision that India will establish a vaccine tracking platform to assess not only the impact of vaccination programme, but also vaccine type and interval between doses: Dr Arora
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It is very imp. in India since around 17-18 cr. people have received only a dose, while around 4 cr. people have received 2 doses. We are over the hump as regards Delta variant, which swept very ferociously across India, with peak of 4 lakh+ cases in May 1st wk: Dr Arora
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A PGI Chandigarh study very clearly shows that vaccine effectiveness was 75% for both partially immunized and fully immunized; so at least in the short run, effectiveness was similar whether you are partially or fully vaccinated: Dr. N.K. Arora

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This also meant that even if you received only one dose, still you are protected: Dr. Arora

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https://twitter.com/PIBMumbai/status/1404844780547280900?s=20

3-4 days ago, another very imp study by CMC Vellore which covers most of the current epidemic wave experienced in April and May, shows that if somebody is partially immunized, vaccine effectiveness of COVISHIELD is 61% and with 2 doses, the effectiveness is 65%: Dr. Arora
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In sum:
- Decisions based on scientific evidence
- Adenovirus vectored vaccines behave differently in different contexts since background circulation of the virus on which the COVID antigen is put in are different

:Dr. Arora
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Two other studies are coming up from two different organizations within Delhi. And both these studies show that breakthrough infection with one dose is around 4%, and around 5% with two doses, basically hardly any difference: Dr. N.K. Arora

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And the other study shows that 1.5% - 2% breakthrough infections

As decisions are taken, investigators are encouraged across the country to see that simultaneously, to look at ground level data from India

- Dr. N.K. Arora

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Tomorrow, we have second meeting of National Vaccine Informatics and Data Analytics; @ICMRDELHI is setting up a Vaccine Tracking Platform - where data from #CoWIN Platform will be superimposed on RT-PCR testing data from labs: Dr. Arora

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From this, we may know whether any of those who got vaccines have got infection and third, this is integrated with disease-related epidemiological information collected by @MoHFW_INDIA and NCDS: Dr. Arora

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https://twitter.com/PIBMumbai/status/1404849738168487937?s=20

These three data sources are harmonized, so as to regularly come back to the community and everybody with the response and impact of various vaccines, including partial vs. complete vaccination, dosage interval and other aspects: Dr. Arora

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This is imp. since vaccination is not a compulsory matter, so monitoring is imp., and as we increase & enlarge vaccination prog., the issue will become more complex, so all vaccines will have to be monitored & India also has a robust system for monitoring AEFI: Dr. Arora

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Is there any proposal to reduce the gap between doses of COVISHIELD, like the UK has done?

Dr. Arora answers: Nothing is cast in stone, COVID-19 and the vaccination is a very dynamic process
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Tomorrow, if the vaccine platform tells us that a narrower interval is better for our people, even if the benefit is 5-10%, the Committee will take the decision on its wisdom; but if it turns out that the current decision is fine, we will continue with it: Dr Arora

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Since ultimately, the health and protection given to our community is what is paramount , that is the most important thing which drives our discussions, generation of new scientific evidence and decision-making: Dr. NK Arora, Chairperson, NTAGI
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