What is currently the government’s strategy regarding Covid-19 vaccines? Two doses? One dose? What are the risks? Who knows what the government’s SAGE committee has advised?

First published in January 2021.

This is how COVID-19 mRNA vaccine BNT162b2 is given, according to detail provided in the UK government’s relevant website:

“COVID-19 mRNA Vaccine BNT162b2 is given after dilution as an injection of 0.3 mL into a muscle of your upper arm.

You will receive 2 injections, given at least 21 days apart.

“Protection against COVID-19 disease may not be maximally effective until at least 7 days after the second dose.

Yet, Sanjay Mishra, Data Scientist and Protein Biochemist at Vanderbilt University, writes in [PMP] today that, “the U.K.’s medical officers have chosen to prioritize distribution of a first vaccine dose to as many people as possible – by delaying the second doses of the Pfizer/BioNTech COVID vaccine up to 12 weeks from the recommended 3-4.

“In the absence of supporting evidence, nothing definitive can be concluded about the depth or duration of protection after just a single dose of currently authorized vaccines.

“Changing the dosing to overcome supply shortages is a contentious and ongoing debate. However, making wrong decisions without adequate scientific evidence could be counterproductive.”

Delaying second COVID-19 vaccine doses will make supplies last longer but comes with risks.
With vaccine shortages looming, experts are debating whether it is important to receive two doses or whether it is better to give one dose to more people and give a second when the supply is better.

The BMJ reported on Tuesday that a leading statistician, Professor Sheila Bird, a former programme leader at the Medical Research Council Biostatistics Unit at the University of Cambridge, has recently written to health secretary Matt Hancock urging him to investigate the effects of extending the gap between the first and second dose of the Pfizer BioNTech vaccine. She said that while deviating from the recommended dosing interval of three weeks could be the right decision that saves more people, the government should ensure they find out the consequences.

The Doctors’ Association says, It is completely unacceptable to ignore the need for a second vaccination. All studies confirm the need for this to provide reliable and lasting immunity.”

Dr Andrew Garrett, Executive Vice President of Scientific Operations at ICON, says: “Currently experimentally controlled data are available for a single dose vaccine regimen in the very short-term only – that is, prior to the planned second dose. These controlled experimental data do support one dose vaccine efficacy for that very limited time period.

“In adopting a policy of delayed second dose boosters, policy makers are having to use their judgment based on previous experiences rather than having access to controlled experimental data.


Professor Stephen Evans, Professor of Pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, says: It is safest and most cautious to use the vaccines in the exact conditions reflecting the trials. However this will never be possible in the real world and the question is how much moving outside the exact conditions is acceptable.

“Pharmaceutical companies are constrained by law and must only make claims that are reflected in the authorisation documents set out by regulatory authorities. Clinicians and health authorities have to take the circumstances they are dealing with into account.

The trials did not compare different dose spacing or compare one versus two doses, so we simply do not know what is ‘optimal’. So, the information directly from the trials is lacking. We have to utilise what we know from science generally. We know that vaccinating only half of a vulnerable population will lead to a notable increase in cases of COVID, with all which that entails including deaths.

“There is no doubt that the UK’s current advice is focussed on public health. The notion that getting one dose results only in protection for 21 days or one month is not biologically plausible.

Expert opinions on the dosage vary. However, this is such a vital issue that there needs to be as much independent evidence and professional scientific assessment of the efficacy and health implications of whichever option is chosen.  

The vaccine manufacturer Pfizer, in a statement, has however repeated that the two doses were needed “to provide the maximum protection”, before reminding health professionals that they “are advised to continue to follow the official guidance on administration of the vaccine.”  

The UK government has made some questionable decisions regarding its pandemic management strategy, this one it can’t afford to get wrong. The manufacturer appears to be clear about its guidance, can the government be equally clear about its rationale?      

UK Vaccination data

People vaccinated in the UK: (up to and including 19 January 2021)

  • First dose: 4,609,740
  • Second dose (fully vaccinated): 460,625


Dr Joe Pajak, Professional experience applied scientific research and development, then director of a national children’s charity, trustee of a disability charity, and governor of NHS foundation trust hospitals.


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🗳️ Matt Hancock

[This piece was first published in PMP Magazine on 21 January 2021. | The author writes in a personal capacity.]

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