Past infection did not provide additional protection from breakthrough infections.
ICMR study on 614 healthcare workers, half of whom each got covishield & covaxin.
Breakthrough infection rate was 13% in those with & without past infection.
1/6
assets.researchsquare.com/files/rs-88876…
ICMR study on 614 healthcare workers, half of whom each got covishield & covaxin.
Breakthrough infection rate was 13% in those with & without past infection.
1/6
assets.researchsquare.com/files/rs-88876…
Breakthrough infection rate is not provided for type of vaccine. Only overall number is given (13%, 81/614)
Antibody levels are seen to drop with time as expected.
Peak antibody levels are lower & the decline faster for covaxin, but this does not imply lower protection.
2/
Antibody levels are seen to drop with time as expected.
Peak antibody levels are lower & the decline faster for covaxin, but this does not imply lower protection.
2/
The reason why a lower antibody level does not mean lower protection is that there are multiple components in the immune system that provide protection. Not all of them are measurable.
Besides, the study does not provide data that lower antibody level led to more infections.
3/
Besides, the study does not provide data that lower antibody level led to more infections.
3/
257 of the 614 had prior infection; the study essentially looked at how the 2 groups did.
This study challenges the existing paradigm that vaccination among those with prior natural SARS-CoV2 virus infection provides superior protection to vaccination in naive individuals.
4/
This study challenges the existing paradigm that vaccination among those with prior natural SARS-CoV2 virus infection provides superior protection to vaccination in naive individuals.
4/
This study is also an indication that reinfections will be commonplace, and indirectly questions the value of giving boosters (Boosters were NOT studied here)
Note that the second dose of vaccine effectively served as the “3rd dose” in the 257 people who had prior infection.
5/
Note that the second dose of vaccine effectively served as the “3rd dose” in the 257 people who had prior infection.
5/
These people (infection+vaccination) however had the SAME rate of breakthrough infections as those who only got vaccination.
In other words, rate of breakthrough infections was the same (13%) whether there were 2 doses or “3” (only in this case, one “dose” was prior virus)
6/
In other words, rate of breakthrough infections was the same (13%) whether there were 2 doses or “3” (only in this case, one “dose” was prior virus)
6/
What does this mean for the road ahead?
1. Repeated infections will occur in environments with high exposure rate (e.g. occupational or behavioural) esp. in closed indoor settings
2. Multiple layers of protection will be needed: masks, ventilation, social restrictions.
7/7
1. Repeated infections will occur in environments with high exposure rate (e.g. occupational or behavioural) esp. in closed indoor settings
2. Multiple layers of protection will be needed: masks, ventilation, social restrictions.
7/7
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