By LAU­RAN NEER­GAARD-As­so­ci­at­ed Press

Mod­er­na hopes to of­fer up­dat­ed COVID-19 boost­ers in the fall that com­bine its orig­i­nal vac­cine with pro­tec­tion against the omi­cron vari­ant. On Tues­day, it re­port­ed a pre­lim­i­nary hint that such an ap­proach might work.

To­day’s COVID-19 vac­cines all are based on the orig­i­nal ver­sion of the coro­n­avirus. But the virus con­tin­ues to mu­tate, with the su­per-con­ta­gious omi­cron vari­ant — and its sib­lings — the lat­est threat.

Be­fore omi­cron came along, Mod­er­na was study­ing a com­bi­na­tion shot that added pro­tec­tion against an ear­li­er vari­ant named be­ta. Tues­day, the com­pa­ny said peo­ple giv­en that be­ta-orig­i­nal vac­cine com­bi­na­tion pro­duced more an­ti­bod­ies ca­pa­ble of fight­ing sev­er­al vari­ants — in­clud­ing omi­cron — than to­day’s reg­u­lar boost­er trig­gers.

While the an­ti­body in­crease was mod­est, Mod­er­na’s goal is to pro­duce a com­bi­na­tion shot that specif­i­cal­ly tar­gets omi­cron. “These re­sults re­al­ly give us hope” that next step will work even bet­ter, said Dr. Jacque­line Miller, a Mod­er­na vice pres­i­dent.

Tues­day’s da­ta was re­port­ed on­line and hasn’t been vet­ted by in­de­pen­dent ex­perts.

COVID-19 vac­cines still are pro­vid­ing strong pro­tec­tion against se­vere dis­ease, hos­pi­tal­iza­tion and death, even against omi­cron. That vari­ant is so dif­fer­ent from the orig­i­nal coro­n­avirus that it more eas­i­ly slips past the im­mune sys­tem’s de­fens­es, al­though stud­ies in the U.S. and else­where show an orig­i­nal boost­er dose strength­ens pro­tec­tion. Some coun­tries of­fer par­tic­u­lar­ly vul­ner­a­ble peo­ple a sec­ond boost­er; in the U.S., that’s any­one 50 or old­er or those with a se­vere­ly weak­ened im­mune sys­tem.

Health of­fi­cials have made clear that giv­ing boost­ers every few months isn’t the an­swer to the mu­tat­ing virus. They’ve be­gun de­lib­er­at­ing how to de­cide if and when to change the vac­cine recipe.

Just switch­ing to a vac­cine that tar­gets the lat­est vari­ant is risky, be­cause the virus could mu­tate again. So Mod­er­na and its ri­val Pfiz­er both are test­ing what sci­en­tists call “bi­va­lent” shots — a mix of each com­pa­ny’s orig­i­nal vac­cine and an omi­cron-tar­get­ed ver­sion.

Why would Mod­er­na’s ear­li­er, be­ta-tar­get­ed com­bo shot have any ef­fect on omi­cron? It in­cludes four mu­ta­tions that both the be­ta vari­ant and the new­er omi­cron have in com­mon, Miller said.

Now Mod­er­na is test­ing a bi­va­lent shot that bet­ter tar­gets omi­cron — it in­cludes 32 of that vari­ant’s mu­ta­tions. Stud­ies of two boost­er dos­es are un­der­way in the U.S. and Britain; re­sults are ex­pect­ed by late June.