Are two COVID vaccine doses necessary for all?

A research letter in JAMA Research published August 6, 2021 has suggested that one dose of vaccine may be adequate for people who have recovered from COVID-19. The small study of 59 people found that those with previous COVID-19 infection had higher antibody levels after one dose of Pfizer vaccine compared with infection-naive individuals after two doses. SARS-CoV-2 spike IgG levels did not increase after the second dose among those previously infected compared with the first dose.

CDC now recommends booster shot of mRNA vaccine for the immunocompromised

Following FDA’s authorisation for a booster shot for immunocompromised persons, the CDC now recommends that people whose immune systems are compromised moderately to severely should receive an additional dose of mRNA COVID-19 vaccine after the initial 2 doses. The additional dose should be the same vaccine as the initial series and administered at least 4 weeks after completing a primary mRNA COVID-19 vaccine series. The list includes people who have

• Been receiving active cancer treatment for tumors or cancers of the blood
• Received an organ transplant and are taking medicine to suppress the immune system
• Received a stem cell transplant within the last 2 years or are taking medicine to suppress the immune system
• Moderate or severe primary immunodeficiency (such as DiGeorge syndrome, Wiskott-Aldrich syndrome)
• Advanced or untreated HIV infection
• Active treatment with high-dose corticosteroids or other drugs that may suppress your immune response

However, the CDC advises to follow all preventive measures wearing a mask, distancing of 6 feet from others and avoiding crowds and poorly ventilated indoor spaces to protect themselves.

Diagnostic features of vaccine-induced immune thrombocytopenia and thrombosis

A new UK prospective study of 220 confirmed cases of vaccine-induced immune thrombocytopenia and thrombosis (VITT) after having the first dose of the Oxford-AstraZeneca vaccine published in the New England Journal of Medicine, August 11, 2021 has identified five diagnostic criteria that are indicative of definite VITT.

• Time of presentation post-vaccination (5-30 days and not before, or ≤42 days in patients with isolated deep-vein thrombosis or pulmonary embolism)
• Low platelets (<150,000 per cu mm)
• Documented thrombosis
• Very raised D-dimers
• Presence of anti-platelet factor 4 antibodies

If all these criteria are met, it is a definite case of VITT. If one is not met, then the diagnosis is probable, if two are not met, then the diagnosis is possible and if ≥3 are not met than it is unlikely to be VITT and there could an alternative diagnosis. While the overall mortality was 23%, in patients with very low platelet counts (<30,000 per cu mm) and intracranial hemorrhage following thrombosis, the mortality increased to 73%... (NEJM, Medscape).

Continuing microscopic lung damage may explain the persistent breathing problems in long-COVID

A medRxiv preprint study has demonstrated that microscopic damage to the lungs many continue in long COVID, even several months after the initial infection and discharge from hospital. This may explain why some patients continue to have breathing problems for many months.

Examination of bronchoalveolar fluid from 38 patients who continued to experience breathing problems at least three months after they were discharged from hospital showed increase in cytotoxic lymphocytes (especially tissue resident CD8+ T cells), lactate dehydrogenase and albumin (biomarkers of cell death and barrier integrity) in COVID-19 survivors compared to healthy volunteers. These persistent abnormalities in the airway immune-proteome in the post-COVID19 airways correlate with ongoing epithelial damage … (medRxiv, posted August 10, 2021).

With inputs from Dr Monica Vasudev