Ross Clark

Ever since the Oxford-AstraZeneca team announced the results of its Phase 3 trials last November, there has been a suspicion among some that their vaccine is the poor relation of the messenger RNA vaccines developed by Pfizer and Moderna. It might be cheap compared with the others, it might be easy to store and transport, but the results published last November indicated that it had an efficacy of 70 per cent compared with over 90 per cent for Pfizer and Moderna. Even that was questioned when it was pointed out that the 70 per cent figure was arrived at by mixing different trials, involving different quantities of vaccine.

Imperial College’s React study was in the news again this morning. The latest instalment swabbed 167,642 people between 6 and 22 January and found that 2,282 of them tested positive. A weighted average suggested that 1.57 per cent of the population had the virus between those dates. The study concluded: 'Prevalence remained high throughout, but with the suggestion of a decline at the end of the study period'. It led to reports this morning that the latest wave of the epidemic is declining only very slowly. The React study, however, seems to be increasingly out of line with government data on new infections, as picked up through the test and trace system. On 6 January, the seven day average of new infections across the UK stood at 594.6 per 100,000.

Just how strong an immunity do Covid patients develop after they have acquired the infection and how long does it last? The question is vital to the likely future passage of the pandemic, and to how well vaccines will protect us in the long term. Several studies have suggested there is a sharp decline in antibodies to SARS-CoV-2 over time – a paper from Imperial College’s React study in October, for example, revealed that the proportion of the population showing antibodies to the virus declined from 6 per cent in June to 4.4 per cent in September. The researchers were at pains to emphasise that the presence of antibodies does not indicate immunity to Covid-19, but many people have taken it as an indication that immunity to the disease quickly declines after infection.

Yesterday, the news was dominated by Imperial College’s React study which suggested – in contrast to the fall in recorded new infections – that the prevalence of Covid-19 in the general population was either static during the first ten days of lockdown (between 6 and 15 January), or could even have risen slightly. This morning, however, we have a second opinion in the form of the ONS infection survey, which like React is based on testing a randomised sample of the population. It suggests that the prevalence of Covid-19 did indeed fall in the first half of January – but not by all that much. Between 9 and 16 January, the ONS estimates, 1.024 million people in England and Wales were infected, the equivalent to 1 in 55 of the population.

Not for the first time, people could be excused for feeling a bit confused by conflicting data on Covid-19. This morning, many news outlets reported claims from the latest React study that levels of Covid-19 infections are no longer falling and may, in fact, be rising. This is somewhat at odds with government data that shows cases have peaked since the beginning of the third English lockdown. For days, the figure for new infections, as detected by NHS Test and Trace, and published on the government’s Covid-19 dashboard, have been falling. In the past seven days, the number of new infections recorded across the UK was 294,172 — 21.5 per cent down on the previous seven day period. What's going on?

The UK’s decision to lengthen the gap between first and second doses of the Pfizer and AstraZeneca vaccines has been criticised by some. But what if we had a vaccine which only needed one dose, and had been tested on that basis? A vaccination programme could progress far more quickly and without the complication of having to ask people to come back to a clinic a second time. In particular, it would simplify the distribution of vaccines in countries with less-well developed public health systems. That is the promise of the latest vaccine candidate for which results have been reported: the Johnson & Johnson vaccine, which is based on an existing Ebola jab.

The World Health Organisation’s appeal to stop naming variants of Covid-19 after geographical locations evidently cut no ice with the Prime Minister, who warned MPs yesterday about a new Brazilian mutation of the Sars-Cov2-virus. Chief scientific adviser Sir Patrick Vallance later suggested to ITV News that the changes identified in the new variant ‘might make a change to the way the immune system recognises it but we don’t know. Those experiments are underway.’ According to Pfizer last week, its vaccine still offers protection against the newly-identified Kent and South African variants of the Sars-CoV-2 virus. But should we now be worrying that the Brazilian variant will creep through our defences?