Should we not follow a different strategy from the UK when vaccinating?

I would be grateful if Dr Brink could clarify a number of issues in connection with vaccines in general and in respect of the Oxford-AstraZeneca (OAZ) vaccine in particular. In various articles, there are references to ‘efficacy and ‘immunogenicity’ rates for the vaccines. For example, the OAZ vaccine trials which began in April 2020 on 24,000 participants in Brazil and the UK reported an efficacy rate of 62% after the third trial phase. The trials involved participants taking a second dose three to four weeks after the first dose. When a small group was included of 2,300 persons aged 55 and under who had received accidentally a half dose followed by a full dose which resulted in an efficacy rate of 90%, it was calculated that this gave an average efficacy rate of 70%. However, approval by the MHRA was only given on the basis of the main trial involving two full doses taken up to three weeks apart.

The UK, because of its desperate situation due to the sharp rise in infections and deaths, has decided to take desperate measures and vaccinate as many as possible using all available OAZ vaccines thereby delaying receipt of the second dose by 12 weeks instead of four weeks. They do this because ‘studies’ appear to show that the first dose will offer protection after about a week against serious symptoms requiring hospitalisation and that a longer delay might not affect the potency of the second dose. This is supported by the fact that none of the participants in the trials had to be hospitalised. However, the first dose is not guaranteed to give immunity and might also not stop transmission of the virus.

It has to be said that this strategy of delaying the second dose is controversial and there was an article published on 10 January in the Sunday Times naming some of the experts warning against doing this. For example, Professor Herb Sewell of immunology at Nottingham University said that abandoning the 21-day gap was ‘madness’. Prof. Paul Bieniasz, a virologist at Rockefeller University in New York, said the decision had the potential of creating a large population of susceptible hosts with partial immunity. Prof. Robin Shattock in a BBC interview on 31 December also said that the longer a person had even a milder form of the virus in his body, the virus could evolve to resist the body’s defences. It reflects the saying that ‘what does not kill you will make you stronger’ and this may also be the case with a virus. Prof. Raymond Agius of Occupational Medicine at Manchester University said that the UK has an obligation to test fully the effects of any extension of the delay between the two doses beyond the delays used in the vaccine trials. Pfizer for one has stated that the efficacy rates given from their trials are only valid with an interval of three to four weeks between doses.

Bearing in mind that Guernsey is not facing the ‘desperate conditions’ that the UK is experiencing, should we not follow a different strategy from the UK and apply the conditions of a maximum of four weeks between the first and second doses of both the Pfizer & AstraZeneca vaccines as well as the Moderna vaccine when it becomes available?

WILLIAM B. MORRIS,

GY6 8ES.

(Note: this letter was submitted before the island went into lockdown)

Editor’s footnote: Thank you for giving the States of Guernsey the opportunity to respond to your reader’s letter.

The timing of second doses of Covid-19 vaccinations has prompted considerable discussion internationally with all governments needing to consider how data from the clinical trials can be applied in their particular circumstances. All jurisdictions face different challenges in respect of prevalence of the virus in their population, their capacity to administer a large scale vaccination programme and the reliability and timings of vaccination supply. Governments need to balance all of this information to make the decision that is right for their community and that what we’re doing locally.

The vaccinations for the cohorts being delivered at the Community Vaccination Centre (cohorts three to nine) will have no more than six weeks between doses. This is to ensure the most optimal and strategic use is made of the vaccine supply allocated to the Bailiwick in the forthcoming months. The gap between doses followed a detailed evaluation of the data regarding the efficacy of the vaccine with differing timing options.

The first two priority cohorts (care home residents, over-80s and front line health and care workers) will continue to receive their second dose of the vaccine at three- or four-week intervals (depending on the vaccine delivered) as plans were already in place to support this delivery model and to ensure the resilience of our health and care services.

We will, of course, keep the scientific data regarding vaccine efficacy under review and adjust our vaccine delivery model if necessary.