Researchers have identified that a single dose of the AstraZeneca (AZ)/Oxford University or the Pfizer/BioNTech vaccines can ‘significantly’ reduce the risk of COVID-19 infection.

Across two studies, published on the preprint server medRxiv, researchers analysed over 1.6 million test results taken from over 370,000 study participants between 1 December 2020 and 3 April 2021 in the UK.

In one study, researchers found that a single dose of either the AZ/Oxford or Pfizer/BioNTech vaccine cut the risk of all new COVID-19 infections by 65%, also reducing symptomatic infections by 72% and infections without reported symptoms by 57%.

In addition, individuals who had received a second dose of the Pfizer/BioNTech vaccine saw their risk of infection cut by 90%.

The researchers also reported that the vaccines were effective against variants comparable to the UK variant – B.1.1.7 – with similar benefits from the vaccines in reducing new infections in both older individuals (aged 75 years and older) and those under the age of 75 years old.

A second study compared the changes in antibody levels following a single dose of either the AZ/Oxford or Pfizer/BioNTech vaccines, or two doses of the Pfizer/BioNTech vaccine.

In this study, researchers identified a lower antibody response to a single dose of either vaccine in older individuals who had not had COVID-19 previously.

However, antibody responses to two doses of the Pfizer/BioNTech vaccine were ‘high’ across all age groups, with increasing responses in older adults reaching similar levels to those receiving a single dose after prior COVID-19 infection.

A UK-based human challenge study will expose healthy volunteers who have previously had COVID-19 to the virus again, in a bid to gain a deeper understanding of immunity against the novel disease.

The study, based at the University of Oxford and funded by the Wellcome Trust, is seeking to understand how the immune system reacts to a second infection of COVID-19, and will also consider what kind of immune response can prevent a person from becoming reinfected.

The first phase will involve approximately 50% of the participants, all of whom will have previously been naturally infected, and will aim to find out the lowest dose of the virus that can cause replication in the body but produce few or no symptoms.

In the second phase of the study, all participants will be infected with a standardised dose of the virus, that will have been established in phase one.

As part of phase two, researchers will define the baseline immune response prior to infecting participants with COVID-19, and then infect them with the dose chosen in the first phase of the study.

The Oxford researchers will then measure how much of the virus can be detected following infection, then seek to understand what kind of immune response protects against reinfection.

Also during this second phase, the study will measure the immune response at different time points after infection to established what level of immune response is generated by the virus.

Moderna has revealed preclinical data evaluating its South African variant-specific vaccine candidates, with early evidence that the booster jabs may be effective against ‘variants of concern’.

Preclinical data for Moderna’s variant-specific vaccines has been submitted to the preprint server bioRxiv and will also be submitted for peer-review publication, the company said in a statement.

This includes data for two candidates – mRNA-1273.351, which targets the B.1.351 variant first identified in South Africa and mRNA-1273.211, a multivalent booster candidate that combines Moderna’s authorised vaccine against ancestral strain and mRNA-1273.351 in a single vaccine.

According to the preclinical evidence, both booster vaccine candidates increase neutralising titres against SARS-CoV-2 variants of concern in mice.

In particular, the data confirms improved neutralising titres from the mRNA-1273.351 vaccine, with the multivalent vaccine providing the broadest level of immunity.

The company added that a boost at six months with the mRNA-1273.351 candidate closed the neutralising titre gap for the variants of concerns.

In addition, neutralising titres were comparable between the ancestral strain and the B.1.351 variant following a booster dose of mRNA-1273.351.

A study led by Oxford University researchers has found the inhaled asthma medication budesonide can shorten recovery time when administered early to high-risk COVID-19 patients.

Budesonide is being evaluated as part of Oxford University’s Platform Randomised Trial of Interventions against COVID-19 in Older People (PRINCIPLE), which hopes to identify effective COVID-19 treatments for use in the community that can significantly shorten recovery time.

Inhaled budesonide – a type of corticosteroid medication – is commonly used to treat asthma and chronic obstructive pulmonary disease.

The trial involved people who were at high risk of becoming severely ill with COVID-19, including participants aged over 50 who had an underlying health condition and participants aged over 65 with no health issues.

The inhaled asthma drug was given to 751 people within the first two weeks of symptom onset, while 1,028 were assigned to the usual standard of NHS care group.

Based on the interim analysis using data with a cut-off of 25 March 2021, the results showed that the estimated time to self-reported recovery for those using inhaled budesonide was three days shorter than for those in the usual standard of care group.

In addition, 32% of those receiving inhaled budesonide recovered within 14 days and remained well at 28 days compared to 22% in the usual standard of care group.

The researchers also found that 8.5% of the budesonide group were hospitalised with COVID-19 compared with 10.3% of the usual standard of care group, although it is not clear from this interim analysis whether budesonide reduces hospitalisations.

Valneva announced yesterday that a phase 3 trial will compare its COVID-19 vaccine candidate to AstraZeneca’s jab, which is conditionally approved in the EU under the brand name Vaxzevria.

The phase 3 trial of Valneva’s vaccine candidate – VLA2001 – against Vaxzevria will see approximately 4,000 participants receive two doses of either vaccine.

Researchers will then determine the immune response two weeks after the completion of a two-dose immunisation schedule, administered four weeks apart.

The trial, conducted in the UK with support from the National Institute for Health Research (NIHR), is powered to demonstrate superiority of VLA2001 in terms of Geometric Mean Titre (GMT) of SARS-CoV-2-specific neutralising antibodies.

“As COVID-19 continues to impact people’s daily lives, we remain fully focused on developing another safe and efficacious vaccine solution. We believe that VLA2001 has an important role to play including boosters or potential modifications to the vaccine to address variants,” said Thomas Lingelbach, chief executive officer of Valneva.

“The UK has been at the forefront of cutting-edge innovation throughout this pandemic, with Valneva’s vaccine set to be made in Scotland, if approved. We have an incredible infrastructure in place for trialling these extraordinary medical advances, and I am delighted the UK will be home to another promising vaccine trial,” added Nadhim Zahawi, UK Minister for COVID-19 Vaccine Deployment.