People who suffer from an autoimmune disease may benefit from a third dose of the Covid vaccine to protect them from breakthrough infections, a new study suggests.

The vaccine programme is still rolling out in the UK – over 88% of adults have had their first dose and over 72% are now fully vaccinated with two doses. 

Currently, two doses of the vaccine provides 90% protection against hospitalisation against the Delta variant. The latest data from Public Health England and Cambridge University shows that around 60,000 deaths and 52,600 hospitalisations have been prevented by vaccines up to July 23.

However, autoimmune diseases often require treatment that dampens the immune system leaving the immunocompromised still vulnerable to Covid and prompting growing calls for them to get a third dose of the vaccine

Previously medical professionals have been unsure whether Covid vaccines would work on immunocompromised people who take B-cell-depleting drugs, such as rituximab to treat rheumatoid arthritis.

However, a pre-print study from the Medical University of Vienna found patients taking rituximab were still able to develop a humoral and cellular immune response – including the antibody production necessary to fight Covid-19.

As Michael Bonelli, senior author of the Vienna study, explains: “B cells constitute an important cell population for the development of antibodies. We were able to show that more than 50% of patients receiving B-cell-depleting treatment with rituximab still develop antibodies to SARS-CoV-2 [Covid-19], and that there is potentially additional protection via a cellular immune response.”

This underscores the importance of vaccinating immunosuppressed patients against Covid, Bonelli said, while his colleague Daniel Aletaha, head of the university’s division of rheumatology, said they also showed that a third vaccination is sometimes needed for people with autoimmune disease.

“The findings from this study formed the basis for a now completed randomised booster vaccination study, which investigated whether the group of patients receiving rituximab treatment who were unable to produce antibodies following standard vaccination can develop humoral or cellular immunity if given a third vaccination with an mRNA vaccine [such a Pfizer] again or a third vaccination with a vector vaccine [such as AstraZeneca],” Aletaha said.

The findings come as many people remain concerned the UK government’s final easing of restrictions in England on July 19 – dubbed ‘Freedom Day’ by some – came before the nation was fully vaccinated, leaving those who have previously shielded from the virus susceptible to infection.

A third dose of the vaccine would differ from the autumn booster jab that has been suggested for the wider British public by the Joint Committee on Vaccination and Immunisation (JCVI)

According to the JCVI’s interim plan, this booster could be offered as early as September to those living in residential care homes for older adults, all adults aged 70 years or over, adults aged 16 years and over who are considered clinically extremely vulnerable, and frontline health and social care workers.

In the meantime, the researches behind the Vienna study hope their findings will feed into the creation of guidelines for a Covid vaccination strategy for immunosuppressed patients.

A follow-on study will extend the rituximab study to all patients with immunosuppression and different indications from the fields of rheumatology, neurology, haematology and transplantation, they added.