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Different booster to original COVID‐19 vaccine may boost antibody response

The antibody response after a COVID‐19 booster (third dose) vaccine appears to be stronger if the booster is a different vaccine to the first and second dose, according to international research, published in the New England Journal of Medicine. The researchers tested three booster shots, Pfizer (153 recipients), Moderna (154 recipients) and Johnson & Johnson (150 recipients). For all combinations, antibody neutralising titres against a SARS‐CoV‐2 D614G pseudovirus increased by a factor of 4 to 73, and binding titres increased by a factor of 5 to 55. Homologous boosters increased neutralising antibody titres by a factor of 4 to 20, whereas heterologous boosters increased titres by a factor of 6 to 73. T cell responses increased in all but the homologous Johnson & Johnson‐boosted subgroup. “These data suggest that an immune response will be generated for each of these vaccines used as a booster regardless of the primary COVID‐19 vaccination regimen,” the researchers reported.

https://www.nejm.org/doi/10.1056/NEJMoa2116414

Make‐up of gut microbiome may be linked to long COVID risk

The make‐up of the gut microbiome may be linked to a person’s risk of developing long COVID many months after initial infection with SARS‐CoV‐2, suggests research published in Gut. Researchers from the Chinese University of Hong Kong tracked changes in the gut microbiome of 106 patients with varying degrees of COVID‐19 severity, treated at three different hospitals between February and August 2020, and in a comparison group of 68 people who did not have COVID‐19, over the same period. Among those with COVID‐19, stool samples were collected on admission (68), and again after 1 month (64) and after 6 months (68). Stool samples were also collected from 11 patients 9 months later. The researchers checked for the presence of the 30 most commonly reported long COVID symptoms 3 and 6 months after initial COVID‐19 infection. Aerobic capacity and endurance, an indicator of long COVID, was also measured in a 6‐minute distance walk test. Long COVID was reported in 86 (81%) patients at 3 months and in 81 (76.5%) at 6 months. Although initial viral load was not associated with long COVID, their gut microbiome differed from that of patients without long COVID and those who had not had COVID‐19 infection. These patients had a less diverse and abundant microbiome; the gut microbiome of patients who did not develop long COVID was similar to that of those who had not had COVID‐19. Among the bacteria species found in patients with long COVID, 28 were reduced and 14 were enriched both at hospital admission and at 3 and 6 months after hospital discharge. At 6 months, patients with long COVID had significantly fewer “friendly” Faecalibacterium prausnitzii and Blautia obeum and a greater abundance of “unfriendly” Ruminococcus gnavus and Bacteroides vulgatus than people who had not had COVID‐19. On the other hand, the gut microbiome of those who did not develop long COVID showed only 25 changes in bacteria species at hospital admission, with complete recovery after 6 months.

https://gut.bmj.com/content/early/2022/01/05/gutjnl‐2021‐325989