Omicron-specific vaccine boosters are now in humans as trials begin

Clinical trial participants received the first dose of omicron-specific COVID-19 vaccines this week. The wave of cases from the coronaviruses variant appears to be cresting in the US and experts are unsure of what to expect next.

Moderna, Pfizer and BioNTech each announced this week that they had dosed their first trial participants. The vaccine doses were adjusted to match the Omicron spike protein found in the earlier version of the vaccine.

Three doses of existing vaccines are holding up against omicron, according to the companies. The companies say that the doses provide strong protection. According to the data published by the Centers for Disease Control and Prevention, three doses are effective at preventing visits to urgent care clinics and emergency departments. The CDC said that three doses are effective at preventing hospitalization.

However, protection from infection has taken a significant hit from the highly mutated variant. In general, antibody levels that ward off infection naturally wane over time. With so many people boosted months before omicron's peak, defenses are down. Additionally, omicron is able to evade some immune defenses from vaccines and past infections, lowering protection from infection further.

Vaccines offer strong protection against severe disease caused by omicron. According to the CEO of BioNTech, emerging data indicates vaccine-induced protection against infections and mild to moderate disease fades more rapidly than was observed with prior strains. The new vaccine is aimed at spurring a similar level of protection against omicron as it did with earlier versions, but with a longer duration of protection.

Uncertain future

Pfizer and BioNTech are testing their omicron-specific vaccine in a trial with 1,420 participants. Participants are split into three groups. In one group, 615 participants who have had just two doses of the existing vaccines will get one or two omicron-specific boosters. In a second group, 600 people who already have three doses of existing vaccine will get an omicron-specific booster. And in a small third group, 205 people who have not been vaccinated at all will get three doses of the omicron-specific vaccine. The companies hope to have the omicron-specific booster ready for use in March.

Moderna has begun a trial with 600 patients in two groups. One group will include people who have only received two vaccine doses, while the other will include people who have had three. Moderna hopes to have the new vaccine ready by March.

Moderna is evaluating whether to include this omicron-specific candidate in its multivalent booster program.

Bancel has previously talked about Moderna's goal of producing a seasonal shot that would cover seasonal flu and another respiratory virus. The development of such a shot is a long way off.

It is not certain if an omicron-specific vaccine and/or seasonal COVID shots will be necessary. While vaccine makers are preparing for more jabs, experts are not sure what to expect after the current wave. Some experts hoped for a lull in transmission and an end to towering peaks. The World Health Organization points to the continued risk that more variant will emerge that could potentially out compete omicron and derail all our vaccines. Most experts seem to agree on one thing: that the coronaviruses will settle into endemicity at some point. COVID-19 will continue to circulate but at low levels that do not disrupt daily life at a population level or overwhelm health care systems. What will happen until then remains unclear.