There is now mounting evidence that shows that the antibody response from a single dose of either an mRNA or adenovirus-vectored vaccine in a person with prior Covid-19 disease is as good, if not better than, a person with two shots of the mRNA vaccine.
I first alluded to this in a twitter message on May 26, 2021, with reference to my 92-year-old uncle who had contracted Covid-19 and had taken his first dose of the Pfizer mRNA vaccine. I attached with the tweet one of many studies which rationalised this approach with good scientific evidence.
The restricted vaccine supply chain has led to various efforts to consider variable dosing strategies in an effort to budget vaccine doses and administer them to a wider segment of the population. The delayed second dose regime practised firstly and widely in the UK was discussed in an earlier article.
Eric Topol, editor-in-chief of Medscape, on February 10, 2021 asked: “How many studies are needed before we accept that people with prior Covid-19 have a robust immune Ab response to a single dose of mRNA vaccine, like the second dose for those with no prior Covid disease?”
More recently, Michael Mina from the Harvard Medical School, tweeted: “To maximise vaccines to halt Covid-19, look to immunity When someone gets their first dose – they should be offered to take a finger prick blood sample at same time That should be tested for SARS-CoV-2 antibodies If positive, then don’t come back for a second dose.”
The RECoVERED Study Group concluded that “A single dose of BNT162b2 mRNA vaccine up to 15 months after SARS-CoV-2 infection provides neutralizing titers exceeding two vaccine doses in previously uninfected individuals. These findings support wide implementation of a single-dose mRNA vaccine strategy after prior SARS-CoV-2 infection.”
Similar immune responses have been illustrated following a single dose of an adenovirus-vectored vaccine. The authors of the study concluded: “Our data support that a single dose ChAdOx1 nCoV-19 vaccine serves as an effective immune booster after priming with natural SARS-CoV-2 infection up to at least 11 months post infection.”
The health care workers in the study who had recovered from Covid-19 and had a single dose of the AstraZeneca vaccine (Covishield in India), not only produced more antibodies, but also made neutralising antibodies which were active not only against the wild type virus but also against the P1 (Brazil) and B1351 (South Africa) variants of concern (VOC).
Malaysia now has clocked 526,000 cases of Covid-19, with 460,000 recovered cases as of May 26, 2021. There is an opportunity here to save about half a million doses of vaccine which can be offered to other Covid-19 naïve individuals.
These persons would also be saved from the potential experience of Adverse Effects Following Immunization (AEFI), which is more pronounced with the second dose of the vaccines.
I am keeping my fingers crossed and hoping that the Ministry of Health (MOH) and the Special Committee on Covid-19 Vaccine Supply (JKJAV) is up to date with the latest dosing strategies and would not deny my 92-year-old uncle his “vaccine passport” when he turns up at the vaccination centre, not wanting the second dose based on scientific studies.
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