Johnson & Johnson (J&J) has confirmed that new preliminary results from the South African phase 3b Sisonke study demonstrate that a booster shot of the J&J COVID-19 vaccine is 85% effective in preventing hospitalisation for COVID-19.

The study was conducted by the South African Medical Research Council (SAMRC) among healthcare workers in approximately 350 vaccination centres across all nine provinces of South Africa after Omicron became the dominant variant.

The study was compiled from mid-November to mid-December when, according to GISAID, an initiative that provides COVID-19 data, the dominance of the Omicron variant increased from 82% to 98% of COVID-19 cases in South Africa.

In Israel, the Beth Israel Deaconess Medical Center (BIDMC) conducted a second, separate analysis of the immune response to different vaccine regimens, which showed that J&J’s COVID-19 vaccine booster generated a 41-fold increase in neutralising antibodies and a 5-fold increase in T cells against Omicron.

The increase in T cells generated by the J&J vaccine may be key to explaining the high levels of effectiveness against severe COVID-19 disease and hospitalisation in the Sisonke 2 study, as the Omicron variant has been shown to escape neutralising antibodies.

The US Food and Drug Administration (FDA) has granted Pfizer-BioNTech an expanded emergency use authorisation (EUA) for the companies’ COVID-19 booster vaccine to include those aged 12 years and older in the United States.

Following the announcement from the FDA, the time between the completion of the primary series and booster doses is significantly reduced for all eligible individuals. Moreover, the authorisation includes individuals aged between five and 11 who are immunocompromised in certain ways.

As with Pfizer/BioNTech’s initial vaccine, the booster dose will have the same dosage strength of 30µg.

For those aged five years and older, the timeline given for the vaccine to be administered as part of a two-dose series is a total of three weeks between each jab.

In the same age group, 28 days must be allowed before a third dose can be given to those who are immunocompromised in certain ways.

The FDA authorisation is based on information provided by an independent assessment, evaluating the safety and effectiveness of a third dose in adults who have had solid organ transplants.

Previously, FDA authorisation was provided for a booster dose of the Pfizer/BioNTech COVID-19 vaccine for individuals aged 16 and older, while those eligible in the 18-and-older age groups also come under the authorisation, even if they have completed their primary vaccination with a different authorised COVID-19 vaccine.

In December 2021, the US Food and Drug Administration (FDA) approved AstraZeneca’s antibody combination Evusheld for emergency use – the first approved therapy for pre-exposure prophylaxis in the US.

Unlike other approved antibody therapies, which are approved to treat people who are already infected with COVID-19, Evusheld can be given as an intramuscular dose to high-risk adults and adolescents aged 12 and older who have not yet been infected.

“Vaccines have proven to be the best defence available against COVID-19, however, there are certain immune compromised individuals who may not mount an adequate immune response to COVID-19 vaccination, or those who have a history of severe adverse reactions to a COVID-19 vaccine and therefore cannot receive one and need an alternative prevention option,” said Dr Patrizia Cavazzoni, director of the FDA’s Center for Drug Evaluation and Research.

It is estimated that around 2% of the population is at increased risk of an inadequate response to a COVID-19 vaccine, while around seven million people in the US are immunocompromised, including those with blood or other cancers being treated with chemotherapy and those taking medications after an organ transplant.

AZ’s head of biopharmaceuticals R&D Mene Pangalos said the company was “proud to play a leading role in fighting the COVID-19 pandemic”, adding that it was “working quickly” to establish how effective Evusheld is at neutralising the new Omicron variant of SARs-CoV-2.

The FDA acted on data from the ongoing PROVENT phase 3 pre-exposure prevention trial which showed that Evushield slashed the risk of developing symptomatic COVID-19 compared to placebo by 77%.

In December 2021, the UK joined the US and other countries in offering a third, booster dose of a COVID-19 vaccine to all adults aged 18 or over.

The expansion of the booster programme came amid growing fears over the level of protection against the new Omicron variant offered by only two shots of a vaccine.
The UK raised its COVID-19 alert level to level four – or a high or rising level of transmission – for the first time since May 2021.

A report by the UK’s Health Safety Agency (HSA) suggested that Omicron was ‘transmitting more effectively than Delta’, with the HSA estimating that, should the variant continue to grow at its present rate, it would have become the dominant strain in the UK by mid-December.

A study from the University of Oxford reported that current vaccines induced lower levels of neutralising antibodies against Omicron.

The study, using blood samples collected from people who had received two doses of standard COVID-19 vaccination, concluded that the ‘substantial fall’ in neutralising antibodies meant ‘increased infections in previously infected, or vaccinated individuals may be likely’.

Professor of paediatrics and vaccinology, Matthew Snape, said: “We know a ‘third dose’ booster significantly increases antibody concentrations and it is likely that this will lead to improved potency against the Omicron variant.”

In December 2021, Sanofi and GSK announced preliminary data on their
COVID-19 vaccine efficacy as a booster shot.

The VAT0002 extension trial showed neutralising antibodies increased between nine
and 43-fold following a booster shot regardless of whether the participants received the AstraZeneca, Johnson & Johnson, Moderna or Pfizer-BioNTech vaccine, with the data applying across all age groups tested.

The companies’ phase 3 trial – VAT008 – is ongoing but its independent data safety monitoring board has recommended it continue into 2022 in order to collect more data. The board wants the trial to include more COVID-19 naïve participants, which has been proved complicated due to the rising number of infections.

“The preliminary data shows we have a strong booster candidate, whatever primary vaccine you have received.” said Sanofi Pasteur’s Thomas Triomphe. “While pursuing a phase 3 trial is a challenge in a quickly shifting pandemic environment, we look forward to seeing the results to support submissions of our booster vaccine as quickly as possible.”

Roger Connor, president of GSK Vaccines, added: “The initial booster data are promising, and we await the phase 3 results to determine the next steps on making protein-based adjuvanted COVID-19 vaccines available.”

In the VAT0002 booster trial, 521 participants who had been vaccinated according to the approved dosing schedule received a single dose of the Sanofi-GSK vaccine candidate, four and ten months after the primary vaccination.