UK COVID-19 Update: Latest on Antibodies, 'Reassuring' Immune Response in Older People from Pfizer and AZ Vaccines

Peter Russell

April 14, 2021

These are the UK coronavirus stories you need to know about today.

Around Half of UK Population Have Antibodies

Around 1 in 2 people in the UK would have tested positive for antibodies against SARS-CoV-2 towards the end of last month, latest figures suggested.

The latest infection survey by the Office for National Statistics (ONS) found that as of March 28, the estimated positive antibody percentages for each nation were:

  • 54.9% in England

  • 49.1% in Wales

  • 54.5% in Northern Ireland

  • 46.0% in Scotland

A reduction in antibody positivity rates have been seen among older people in recent weeks.

An ONS spokesperson said: "By mid-March we had begun to see a decrease in detectable antibodies amongst age-groups prioritised for vaccination. This trend appears to have reversed slightly, likely reflecting many of these same age groups now receiving their second dose of vaccine.

"There is a clear pattern between vaccination and testing positive for antibodies, however the detection of antibodies alone is not a precise measure of protection granted by vaccines.

"It is possible that antibody levels in some people are now too low to be detected by our tests but still high enough to grant a level of protection."

Kevin McConway, emeritus professor of applied statistics at The Open University, commented that, "overall, because of the balance between increases in antibody positivity from vaccination and infection, decreases in positivity because of natural reduction in antibody levels, and the fact that antibodies aren't the whole story on immunity, it's not possible to say definitely from these results… how close we might be to a level of immunity that will keep infections strongly in check".

Pause in US Rollout of Johnson & Johnson Vaccine

UK experts have been commenting on the decision by The Centres for Disease Control and Prevention (CDC) and US Food & Drug Administration (FDA) to recommend pausing rollout in the US of Johnson & Johnson's Janssen COVID-19 vaccine after 6 cases of cerebral venous sinus thrombosis in combination with thrombocytopenia in people who received the vaccine.

All the cases occurred in women between the ages of 18 and 48.

The CDC said it was acting "out of an abundance of caution".

Johnson & Johnson (J&J) issued a statement on Monday saying it would delay rollout of the vaccine in Europe.

Adam Finn, professor of paediatrics at the University of Bristol said that the 6 cases reported after involving J&J's Janssen vaccine "echoes recent events in Europe around the Oxford/AstraZeneca vaccine".

He said: "These two vaccines are similar in the way they work, using two different adenovirus vectors to carry the coronavirus spike protein gene into the recipient's arm."

Although it was too soon to draw firm conclusions, "this development does raise the possibility that at least some adenovirus vectors either of themselves or in combination with the SARS CoV-2 S protein gene can cause this idiosyncratic reaction in a very small proportion of individuals", he added.

Eleanor Riley, professor of immunology and infectious disease at the University of Edinburgh, told the Science Media Centre that "it remains the case that for the vast majority of adults in Europe and the USA, the risks associated with contracting COVID-19 far, far outweigh any risk of being vaccinated".

The UK has ordered 30 million doses of the J&J vaccine which has yet to be approved by regulators.

Prof Anthony Harnden, deputy chair of the Joint Committee on Vaccination and Immunisation, said depending on the outcome of any review, "there may be implications for the recommendation of the Janssen vaccine in the younger age groups in the UK where the risk from severe COVID is much less than in older age groups and in those with underlying illnesses".

Meanwhile, Denmark has become the first country to completely stop using the AstraZeneca/Oxford vaccine because of concerns about blood clots.

The head of Denmark's health authority said he did not rule out using the vaccine again in the future if another wave of the pandemic occurred, the BBC reported.

Expansion of Alternating Vaccine Trial

Recruitment has begun for a new arm of the Com-COV trial investigating 'mixing and matching' of COVID-19 vaccines.

The first phase of the study by the University of Oxford has involved alternating first and second doses of the Pfizer/BioNTech and AstraZeneca/Oxford vaccines.

The next stage will include vaccines made by Moderna and Novavax.

Researchers said they planned to recruit 1050 adults aged over 50 who had already received a first dose of vaccine. Participants would be randomly assigned to either receive the same vaccine for their second dose, or a dose of the Moderna or Novavax vaccine.

The 'non-inferiority' study will compare immune system responses to benchmarks reported in previous clinical trials of each vaccine.

Chief investigator Prof Mathew Snape of the Oxford Vaccines Group said a positive outcome could "create resilience within the system in the event of a shortfall in availability of any of the vaccines in use".

First results from both arms of the trial are expected between May and July.

Strong Immune Response from Vaccines in Over 80s

A study led by the University of Birmingham found strong immune responses in people aged 80 and over who had received a single dose of either the Pfizer/BioNTech or AstraZeneca/Oxford vaccines five weeks previously.

Results published in a preprint found antibody responses in 93% of those injected with Pfizer's BNT162b2 mRNA vaccine, and 87% in those who had AstraZeneca's ChAdOx1 adenovirus vaccine.

However, spike-specific T-cell responses were found to be three times higher in recipients of the AstraZeneca vaccine compared to the Pfizer vaccine.

Evidence of previous natural infection was associated with a large increase in immune response.

The research was based on 165 participants, 8 of whom had already been infected naturally with SARS-CoV-2.

Commenting on the study for the Science Media Centre, Eleanor Riley, professor of immunology and infectious disease at the University of Edinburgh, said the data was "reassuring".

She added: "Assuming that a similar effect is seen after two vaccinations (as expected from the clinical trial data), this really underscores the importance of having the second vaccination."

Other COVID News

  • The European Union said it had administered 100 million COVID vaccinations. The European Commission president, Ursula von der Leyen tweeted that it was "a milestone we can be proud of". She also announced that the bloc had agreed a 25% increase in the number of doses of the Pfizer/BioNTech in the second quarter of the year, bringing the total number of doses to 250 million.

  • Religious leaders published guidance for Muslims confirming that having a COVID-19 vaccine was permissible during Ramadan. Zara Mohammed, secretary general of The Muslim Council of Britain, said: "The message for vaccination during Ramadan is clear: vaccines don't invalidate your fast."

  • The Welsh Government said it had accepted advice from the Joint Committee on Vaccination and Immunisation that people over 16 who live with individuals with severely weakened immune systems should be prioritised for COVID-19 vaccination. The advice reflected growing evidence that the vaccination may reduce a person's likelihood of passing on the SARS-CoV-2 virus.

  • Plans to hold this summer's Tokyo Olympic and Paralympic games should be reconsidered, experts said. An editorial in The BMJ by Kazuki Shimizu at the London School of Economics and Political Science and colleagues warned that with uncertainty remaining about the pandemic, such a mass gathering might be "neither safe nor secure".

  • Physical inactivity is associated with a higher risk of severe COVID-19, according to a study in the British Journal of Sports Medicine . It found that consistent inactivity increased the odds of hospitalisation 2.26 fold compared with people who met exercise guidelines. The study examined data on 48,440 adults who had a COVID-19 diagnosis between January 1 and October 21, 2020.

  • Older people without smartphones risk being discriminated against at pubs and restaurants who are using online ordering after being allowed to re-open, a charity has warned. Caroline Abrahams from Age UK said it "risks widening the digital divide and reducing the opportunities for some older people to enjoy socialising once again".

Every Adult Vaccinated on the UK's Remotest Island

Two nurses completed vaccination for the entire adult population of Fair Isle in one morning, the BBC reported.

The remote Scottish island, located between Orkney and Shetland, has a population of just 48.

Vials of the AstraZeneca/Oxford vaccine were flown in by plane this week for the second dose.

John Best, the oldest resident on the island, renowned worldwide for its knitwear, said he felt he was now living in "one of the safest places in the country".


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