Focus on Arts and Ecology

Dear Jon,

With the emergence of the omicron variant of SARS-CoV-2, emphasis on third-dose vaccinations has intensified in many countries. In Israel—the first country to offer third-dose booster shots to all adults—the discussion has now shifted to the possibility of offering a fourth dose. In the US, the Centers for Disease Control and Prevention are now urging all adults (aged 18 years and older) to have booster shots, with the UK set to follow suit in early 2022. Even before omicron emerged, questions abounded over whether a mix-and-match strategy for third-dose vaccines would generate a better immune response than a third dose of the same vaccine given initially.

In the COV-BOOST trial, published this week in The Lancet, seven different COVID-19 vaccines were given as a third-dose to nearly 3000 adults who had received two doses of either the ChAdOx1 nCov-19 (Oxford-AstraZeneca) or BNT162b2 (Pfizer-BioNTech) vaccines 2-3 months earlier. The bottom line of the trial was that the third-dose vaccines—whether with the same or a different vaccine—boosted neutralising antibody and T-cell responses to both wild-type and variant viruses (with somewhat blunted responses to delta), regardless of age. The exception was the inactivated VLA2001 (Valneva) vaccine when given after two doses of BNT162b2.

A third dose of CoronaVac—the world’s most widely offered COVID-19 vaccine—also effectively boosted immune responses, according to a trial from China published this week in The Lancet Infectious Diseases. CoronaVac was also shown to be immunogenic in patients with immune-mediated rheumatic diseases in a study from Brazil published in The Lancet Rheumatology, with the generation of robust neutralising antibody responses seen after a single dose in those with prior SARS-Cov2 infection.

These studies leave little doubt about the ability of third-dose vaccines to ramp up anti-COVID-19 immunity. Yet, the super-charging of booster programmes has reinvigorated debate over vaccine equity, with a concern that the expansion of booster vaccines in high-income countries will further exacerbate the global vaccine imbalance.

Yours sincerely,

Heather Van Epps
Editor-in-Chief, The Lancet Rheumatology

P.S. The COVID-19 Resource Centre is updated daily with the latest Articles, News, expert Commentary, Correspondence, Chinese translations, and more, from across the Lancet family of journals. All of our COVID-19 content is free to access.

(Sources: The Lancet)