• Trial demonstrates that after receiving first vaccination dose, patients who have previously been infected with COVID-19 show a 59-fold higher antibody count than patients with no infection history.
• Findings of the London-based academic research unit, Richmond Research Institute (RRI) suggest a second vaccination for previously infected individuals may not be necessary in the short-term.
• Study could have implications for the UK vaccination strategy, enabling the prioritisation of individuals who have never been infected previously by the virus.

The results: Do COVID-19 patients require a second vaccine dose?

The research suggests that patients who have previously been infected with COVID-19 produce significantly more antibodies after one vaccine dose – 59 times more – to fight a COVID-19 infection than patients who have not previously contracted COVID-19. These results included both recipients of the Oxford-AstraZeneca vaccine and the Pfizer-BioNTech vaccine.

As a result, patients who have previously had COVID-19 could potentially be de-prioritised for a second dose in order to focus on other groups and vaccinate a broader population.

Further research should be conducted to test these findings on a larger scale; however, this may have significant implications for governments’ vaccine strategies across the world and be especially valuable information for those regions that struggle with vaccine supply.

How the RRI conducted the research

At the onset of the pandemic in March 2020, RRI quickly initiated COVID-19 testing for staff, research participants and visitors to Richmond Pharmacology’s London Bridge clinical research site. Over that period, sixty-four individuals aged 22 to 63 years received at least one vaccine dose. RRI analysed the data produced by this testing in an attempt to understand whether individuals who had previously been infected with COVID-19 could be deprioritised for receiving a second vaccine inoculation, and whether the answer to this question is dependent on the specific vaccine provided.

Of the analysed patients, nineteen vaccinated individuals had previous COVID-19 infection, and those previously infected were vaccinated within an average 6.25 months after infection (range: 2 to 11 months).

Twenty-four individuals received the Pfizer-BioNTech (BNT162b2-mRNA) vaccine and 40 received the Oxford-AstraZeneca (ChAdOx-1-S) vaccine.

Dr Jorg Taubel, CEO of Richmond Pharmacology and a scientific lead at RRI, said:

“This research highlights that there are still many questions to be asked about the most effective vaccine strategy for national populations. While we have made significant findings about the levels of antibodies developed, we recognise our study is small. However, the results are striking and the cohort we tested is well characterised. We encourage the Government and wider research environment to explore this issue further to test our findings.”

“If these results can be validated among a larger sample group, it may mean countries can de-prioritise those who have had COVID-19 for their second vaccinations and reach their wider priority populations.