January 2023: Bivalent Omicron BA.1–Adapted BNT162b2 Booster in Adults Older than 55 Years
The issue
Older adults already boosted with the original Pfizer‑BioNTech vaccine begin to lose protection as immune‑escape Omicron strains circulate. A phase‑3 trial in 1 ,846 people over 55 found that a bivalent Omicron BA.1–adapted booster (15 µg ancestral + 15 µg BA.1, 30 µg total) raised neutralising activity against BA.1 56 % higher than another 30‑µg dose of the original vaccine, and the 60‑µg bivalent and 60‑µg monovalent BA.1 shots performed even better. The adapted boosters maintained responses to the ancestral strain and broadened coverage to BA.4/5 and BA.2.75 sub‑variants.
What do I need to know?
Participants had already received three 30‑µg BNT162b2 doses a median 6.3 months earlier. One month after the fourth dose, both bivalent strengths—and the 60‑µg monovalent BA.1—met U.S.‑FDA criteria for superiority or non‑inferiority on all primary immunogenicity goals. Local pain and transient fatigue were the commonest reactions; serious events were rare and similar to the original booster. Mild‑to‑moderate side‑effects resolved within days, and no severe Covid‑19 occurred during early follow‑up.
Potential risk of waning Covid‑19 immunity
Older adult had three Pfizer doses, last one less than six months ago, no chronic illnesses.
Recommended Actions
Mark the calendar and plan an updated booster once six months have passed.
Use masks in crowded indoor spaces and keep rooms well ventilated.
Track local variant trends via health‑department updates.
Imminent risk of waning immunity
Six months or more since the third dose, or moderate comorbidities such as diabetes or heart disease.
Recommended Actions
Request a bivalent Omicron‑adapted booster (either 30‑µg or 60‑µg) at the next visit.
Review current medications and schedule the shot on a low‑activity day in case of fatigue.
Keep flu and RSV vaccinations current to reduce co‑infection risk.
Confirmed high‑risk situation
More than twelve months since the last booster, or immunosuppression, long‑term‑care residency, or recent Covid‑related hospitalization.
Recommended Actions
Receive the bivalent BA.1 (or currently available BA.4/5) mRNA booster as soon as possible and record lot number and date.
Order serology or T‑cell testing only if part of a clinical plan; adapted boosters already meet immune‑response targets.
After vaccination, monitor for rare serious symptoms such as chest pain or persistent palpitations and seek care promptly if they occur.
What can I do?
Ask your clinician, “Am I at potential, imminent, or confirmed risk from waning immunity, and which updated booster suits me?” Bring your vaccination card and a list of health conditions. Expect arm soreness and brief fatigue—rest, hydrate, and use acetaminophen if necessary. Caregivers can help schedule the appointment, arrange transportation, and note any side‑effects to discuss at follow‑up.
