New booster campaign relies on superseded vaccines

The appearance of a new Covid-19 variant prompted the government to launch the autumn booster campaign this week, though it appears it will not be using vaccines specifically tailored to the currently dominant variants. While infections remain at relatively subdued levels, the latest figures suggest they are on the increase, with hospital admissions up 30% in England and 200% in East Sussex. Text by Nick Terdre, research and graphics by Russell Hall.

Following the emergence of a new variant, BA.2.86, which is causing concern in medical circles, the Department for Health and Social Care (DHSC) brought forward the launch of the autumn booster campaign in England to last Monday, 11 September, in what it called a precautionary move. Adult care home residents and the housebound are the first to receive a vaccine.

From 18 September the NHS will start to invite people in priority order of risk. (Details on who is eligible can be found on the Sussex Health & Care website.)

“As our world-leading scientists gather more information on the BA.2.86 variant, it makes sense to bring forward the vaccination programme,” health minister Maria Caulfield said. “It is absolutely vital the most vulnerable groups receive a vaccine to strengthen their immunity over winter to protect themselves and reduce pressure on the NHS.”

However, it seems that the vaccines specifically tailored to combat the currently most common strains of Covid-19, as well as BA.2.86 – which by offering better protection will also reduce the burden on the NHS this winter – may not, at least initially, be used.

The dominant strain until recently was XBB.1.16, but in late August this was overtaken by EG.5.1. These, as well as BA.2.86, are part of the Omicron stable, which replaced Delta as the dominant Covid-19 family in late 2021 (see the BA.2 family tree below).

Updated vaccines

Two leading vaccine developers, Pfizer/BioNTech and Moderna, have both developed updated versions of their Covid-19 vaccines specifically aimed at the currently dominant strains, which were approved for use in the US this week by the US Centers for Disease Control and Prevention (CDC) following encouraging results in tests.

The updated Pfizer and Moderna vaccines, tailored to combat the XBB.1.5 lineage, proved to generate an improved antibody response to various related sub-lineages, including XBB.1.16 and EG.5.1. Pfizer’s vaccine – Comirnaty Omicron XBB.1.5 – has been authorised for use in the EU following recommendation by the Committee for Medicinal Products for Human Use of the European Medicines Agency, which yesterday gave the thumbs-up for Moderna’s Spikevax XBB.1.5.

Pfizer’s vaccine was approved for use in the UK by the Medicines and Healthcare products Regulatory Agency (MHRA) on 5 September under the so-called EC Decision Reliance Procedure whereby the agency can rely on European Commisssion approval. The EC gave the go-ahead to Moderna’s vaccine today, as did the MHRA with admirable swiftness.

It remains to be seen if the DHSC will make every effort to use the updated vaccines rather than the superseded ones in the autumn campaign. Pfizer said on 30 August it was ready to ship the new product from its factory in Belgium, but obviously it will take time to distribute it to local surgeries, pharmacies and other vaccination centres.

Test success

In test results shared with the US CDC – see graphic below – Pfizer demonstrated greater virus neutralisation with Comirnaty Omicron XBB.1.5 compared with the previous versions developed for the original Wuhan virus and Omicron BA.5: a 4.6-fold better virus neutralisation against the XBB.1.5 infection (ie 2,043 ÷ 440), 7.1-fold better against EG.5.1 and 3-fold better against BA.2.86.

For its part Moderna’s Spikevax proved to boost antibody generation in the face of various XBB strains — up by 9.7 times against XBB.1.16, 11 times against EG.5.1 and 8.7 times against BA.2.86 as a fifth dose in those who have already received the full course of four jabs.

Both companies’ updated products are monovalent vaccines, which target a single strain of the virus. They are more effective against the currently circulating lineages than their previous bivalent versions – targeting two strains – which were adapted to previously dominant forms of the virus, the original Wuhan virus from 2020 and Omicron BA.5 which was circulating in the second half of 2022.

New variant

New variants are always evolving, though most are unsuccessful and soon die out. However researchers’ attention was called to BA.2.86, which has been dubbed Pirola, due to the many mutations it displayed, which suggested it might be unusually good at evading immunity.

It first hit the news last month even though only six cases had been identified by genomic sequencing. They were spread out internationally — three in Denmark and one each in the Israel, the US and the UK. Only the US case had a recent travel history, from Japan, which led the UK Health Security Agency (UKHSA) to conclude there was established international transmission and community transmission within the UK.

As of 11 September 37 cases had been sequenced in England, according to the UKHSA. These included 28 in a Norfolk care home, which led the agency to conclude on the basis of lab analysis that BA.2.86 “may be sufficiently transmissible to have impact in close contact settings.”

No known cases have yet been identified in the South East, but six have been in London, one in the North West, one in the North East and one other in the East of England. Of the 37 cases identified in England, seven were hospitalised, two tested in an emergency department, and one has unknown hospital status. There have been no deaths due to Covid-19 among these cases.

As of 11 September again, five BA.2.86 cases had been reported by Public Health Scotland, but none in Wales or Northern Ireland.

In a technical briefing, the UKHSA said that while the detection of multiple unlinked cases in different regions suggested that community transmission was established, this did not indicate that BA.2.86 had a growth advantage over other variants circulating in the UK.

Covid cases up

It also noted that there were early indications of an increasing number of Covid-19 cases in the UK, though there was insufficient data to link this to BA.2.86. Figures released today show a 30% jump in Covid-19 hospital admissions in England, up from 2,531 in the week to 1 September to 3,287 in the week to 8 September.

The number of Covid-19 patients in English hospitals was 3,356 in the week to 10 September, a 15% rise from 2,915 in the previous week.

Locally there were 13 Covid-19 patients in East Sussex hospitals on 10 September, down from 18 a week before, none of them in critical care. However, in the week to 8 September, East Sussex hospital admissions leapt by 200% , to 27 from nine the week before.

In the week ending 1 September there were no Covid-19 deaths in Hastings or Rother.

An upturn in infections in England is also indicated by the R value, or average reproduction rate per infected person, which was estimated at 1.23 on 8 September, up from 1.08 a week before. A figure greater than 1 indicates increasing prevalence.

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