Kenyans vaccinated with Covishield may need boaster shot

A study in India has suggested people immunized with the Covishield Covid 19 vaccine may need a booster dose.

The first dose of the Covishield vaccine, the most dominant in Kenya; the study says was seen to produce adequate protection.

But a second dose, four weeks later, did not increase protective antibodies and in fact a significant decline was noted.

“Of concern, the second dose did not boost the neutralizing antibodies, but, a 1.75 fold reduction was noted,” say the study by Bharati Vidyapeeth Medical College in Pune, India.

Consequently, the research team is advising a booster shot for people especially who have not had prior Covid 19 infection.

“For the generation of higher antibody titers and possible longer persistence at raised levels, a booster dose will be required,” advises the study.

Covishield is the brand name of the AstraZeneca Covid 19 vaccine manufactured by the Serum Institute of India, and the most dominant in Kenya and most African countries.

It consists the first 1.02 million doses received in Kenya in March through the World Health Organization coordinated Covax facility.

After suspending exports for the last several months India has announced resumption in October which is likely to see Covishield retain dominance in Africa.

Covishield however is not recognized in some European countries.  European and developed countries use the AstraZeneca version, Vaxzervria, mainly manufactured in the UK.

Kenyans and other people vaccinated with Covishield may have problems entering some of the developed countries where the vaccine is not recognized.

In this first study to evaluate the level of protection in people vaccinated with Covishield, the authors conclude a booster shot will be necessary.

The study had involved 187 health workers who had received Covishield vaccine at the Bharati Vidyapeeth Medical College and hospital in Pune, India.

The study was posted last week (22nd September 2021) at The Lancet Preprints. This, the authors say is the first systematic, real-world assessment with Covishield showing adequate protection.

However they suggest more evaluation to determine the cause of protective decline after the second dose in some recipients.

In a June 2021 study, Kenya’s Ministry of Health had recommended that local Covid 19 vaccination plans put into account the huge number of Kenyans already exposed to the virus.

It had estimated about 39 million or 75 per cent of Kenyans had been exposed to the virus by June this year, consequently giving them some type of protection.

The high rate of exposure, the study suggested could have been the cause of a suppressed fourth wave in the middle of the year.

“Our predictions of current population exposure in Kenya (75 per cent June 1st) have implications for the next wave and control strategies including vaccinations,” said the Kenya study.

But the India study is also aware of the impracticability and cost of first testing people for Covid antibodies before vaccination. Hence this, they say would make it difficult to single out never exposed persons for a booster jab.

The team says Covishield had elicited high protection among the vaccinated health workers in India, but suggests more investigation on the noted decline after the second dose.

“Relation of dose interval and post-2nd decline in Nab titers in pre-positives needs evaluation.”

By Gatonye Gathura

The Covishield report is available here: or



About Gatonye Gathura 142 Articles
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