An experimental vaccine targeted at the South African strain of Covid-19 has produced antibodies in laboratory mice, its maker said last night, offering an early sign that it could protect humans against the variant.
Moderna is developing a vaccine to target the B.1.351 variant, which was discovered in South Africa, as well as a multivalent vaccine that combines its original vaccination with the South Africa-specific jab. The company is the first to produce a vaccine designed for the variant detected in South Africa and said its pre-clinical trials in mice for both jabs “improved neutralising titers”, meaning that antibodies detected in the blood increased.
The multivalent vaccine would provide the broadest level of immunity, according to Moderna.
Sadiq Khan, the mayor of London, has revealed that the South African strain has now been detected in four London boroughs. NHS Test and Trace is providing additional door-to-door testing in Southwark after a case was detected in Rotherhithe, southeast London.
A case was also detected in Barnet, north London, on Wednesday, though officials insist it is unrelated to the cluster south of the Thames. Surge testing has already been initiated in Lambeth and Wandsworth after the B.1.351 variant, discovered in South Africa, was found by contact tracers. There have been 44 confirmed cases in the two boroughs, with a further 30 probable cases detected.
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Khan said: “Extra testing will now take place in a targeted area in SE16, Southwark — after a confirmed case of the COVID19 variant first discovered in South Africa has been found. If you’re asked to take a PCR test, it’s crucial that you do so to help track and limit any cases.”
Britain’s ability to control dangerous coronavirus variants is facing its biggest test so far as health officials scramble to contain an outbreak in south London affecting a care home and two schools.
Downing Street said that the cluster was being taken “very seriously” but residents have not not been told to stay at home because public health officials are confident that they can contain the chain of infection.
The surge testing of thousands of residents with no symptoms in Lambeth and Wandsworth will see if the outbreak has spread further than thought, which could set back efforts to exit the lockdown as planned.
Although studies have not been concluded, the B.1.351 variant is thought to reduce the effectiveness of vaccines and tough border controls have been imposed on travellers from affected countries to slow its spread. The south London outbreak is thought to have been started by a traveller who arrived from another African country in February, around the time the government introduced hotel quarantine.
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It is thought that although the traveller did self-isolate, they passed the virus to a member of their household, who then introduced it to a care home in Lambeth. So far 23 of the 44 confirmed cases have been in this care home, 13 in staff and ten in residents. Six of the ten infected residents had received one dose of the Oxford-AstraZeneca vaccine more than two weeks beforehand.
From the care home, the virus is thought to have spread to two primary schools in neighbouring Wandsworth. Officials are testing the contacts of cases and the contacts of those contacts, even if they have no symptoms.
Boris Johnson’s spokesman said: “This is something that we are taking very seriously and the effective surge testing processes that we have in place have been working well.”
A government source said: “Nobody is panicking. This is the system functioning as intended.”
How jabs measure up against the strains
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Pfizer-Biontech
40m doses ordered
Trial efficacy 95 per cent against symptomatic illness
Real-world efficacy against variants In Israel, where the UK variant is dominant, the vaccine appears to provide 97 per cent protection against symptomatic illness. But Israeli data suggests that the South African variant can break through its protection. It accounts for 0.7 per cent of all cases there but 5.4 per cent among the vaccinated.
Oxford-AstraZeneca
100m doses
Trial efficacy Initially estimated at 70 per cent, though later data suggests that a longer delay between doses of the vaccine improves its efficacy.
Efficacy against variants Later analyses found 75 per cent efficacy against the UK variant. A small trial in South Africa implied just 10 per cent efficacy against their variant. Most scientists think it is likely that it offers far higher protection against severe illness.
Moderna
17m doses
Trial efficacy 95 per cent
Efficacy against variants Laboratory trials suggest antibody levels are significantly lower against variants, with a 12.4-fold reduction against the South African variant. However, the company is working on new vaccines that it hopes would be effective.
Johnson & Johnson
30m doses
Trial efficacy 72 per cent
Efficacy against variants When J&J reported the results of its trial, carried out after South Africa had been swept by the variant, it released data from each country separately. For the US, the vaccine stopped 72 per cent of symptomatic illness. For South Africa, it fell by 15 percentage points.
Novavax
60m doses
Trial efficacy 96 per cent
Efficacy against variants Preliminary results suggest that the Novavax jab is 96 per cent effective against the original variant, 86 per cent against the UK variant and 60 per cent against the South African variant. There is little real-world data against the Brazilian Manaus variant. All vaccines that have been tested in lab studies show reduced production of antibodies against variants. The results suggest that even if they allow more infection, protection should remain high against severe illness.
