By LAU­RAN NEER­GAARD and MIKE STO­BBE | AS­SO­CI­AT­ED PRESS

(AP) — Most Amer­i­cans should be giv­en the Pfiz­er or Mod­er­na vac­cines in­stead of the John­son & John­son shot that can cause rare but se­ri­ous blood clots, U.S. health of­fi­cials said Thurs­day.

The strange clot­ting prob­lem has caused nine con­firmed deaths af­ter J&J vac­ci­na­tions — while the Pfiz­er and Mod­er­na vac­cines don’t come with that risk and al­so ap­pear more ef­fec­tive, said ad­vis­ers to the Cen­ters for Dis­ease Con­trol and Pre­ven­tion.

The pan­el rec­om­mend­ed the un­usu­al move of giv­ing pref­er­ence to the Pfiz­er and Mod­er­na vac­cines, and late Thurs­day the CDC’s di­rec­tor, Dr. Rochelle Walen­sky, ac­cept­ed the pan­el’s ad­vice.

Un­til now the U.S. has treat­ed all three COVID-19 vac­cines avail­able to Amer­i­cans as an equal choice, since large stud­ies found they all of­fered strong pro­tec­tion and ear­ly sup­plies were lim­it­ed. J&J’s vac­cine ini­tial­ly was wel­comed as a sin­gle-dose op­tion that could be es­pe­cial­ly im­por­tant for hard-to-reach groups like home­less peo­ple who might not get the need­ed sec­ond dose of the Pfiz­er or Mod­er­na op­tions.

But the CDC’s ad­vis­ers said dur­ing a meet­ing Thurs­day that it was time to rec­og­nize a lot has changed since vac­cines be­gan rolling out a year ago. More than 200 mil­lion Amer­i­cans are con­sid­ered ful­ly vac­ci­nat­ed, in­clud­ing about 16 mil­lion who got the J&J shot.

New da­ta from un­prece­dent­ed safe­ty track­ing of all those vac­ci­na­tions per­suad­ed the pan­el that while the blood clots linked to J&J’s vac­cine re­main very rare, they’re still oc­cur­ring and not just in younger women as orig­i­nal­ly thought.

In a unan­i­mous vote, the ad­vis­ers de­cid­ed the safer Pfiz­er and Mod­er­na vac­cines are pre­ferred. But they said the shot made by J&J’s Janssen di­vi­sion still should be avail­able if some­one re­al­ly wants it — or has a se­vere al­ler­gy to the oth­er op­tions.

“I would not rec­om­mend the Janssen vac­cine to my fam­i­ly mem­bers” but some pa­tients may -- and should be able to -- choose that shot, said CDC ad­vis­er Dr. Beth Bell of the Uni­ver­si­ty of Wash­ing­ton.

The clot­ting prob­lems first came up last spring, with the J&J shot in the U.S. and with a sim­i­lar vac­cine made by As­traZeneca that is used in oth­er coun­tries. Even­tu­al­ly U.S. reg­u­la­tors de­cid­ed the ben­e­fits of J&J’s one-and-done vac­cine out­weighed what was con­sid­ered a very rare risk — as long as re­cip­i­ents were warned.

Eu­ro­pean reg­u­la­tors like­wise con­tin­ued to rec­om­mend As­traZeneca’s two-dose vac­cine al­though, be­cause ear­ly re­ports were most­ly in younger women, some coun­tries is­sued age re­stric­tions.

COVID-19 caus­es dead­ly blood clots, too. But the vac­cine-linked kind is dif­fer­ent, be­lieved to form be­cause of a rogue im­mune re­ac­tion to the J&J and As­traZeneca vac­cines be­cause of how they’re made. It forms in un­usu­al places, such as veins that drain blood from the brain, and in pa­tients who al­so de­vel­op ab­nor­mal­ly low lev­els of the platelets that form clots. Symp­toms of the un­usu­al clots, dubbed “throm­bo­sis with throm­bo­cy­tope­nia syn­drome,” in­clude se­vere headaches a week or two af­ter the J&J vac­ci­na­tion — not right away — as well as ab­dom­i­nal pain and nau­sea.

While it’s still very rare, the Food and Drug Ad­min­is­tra­tion told health care providers this week that more cas­es have oc­curred af­ter J&J vac­ci­na­tions since the spring. They oc­cur most in women ages 30 to 49 -- about once for every 100,000 dos­es ad­min­is­tered, the FDA said.

Over­all, the gov­ern­ment has con­firmed 54 clot cas­es— 37 in women and 17 in men, and nine deaths that in­clud­ed two men, the CDC’s Dr. Isaac See said Thurs­day. He said two ad­di­tion­al deaths are sus­pect­ed.

The CDC de­cides how vac­cines should be used in the U.S., and its ad­vis­ers called the con­tin­u­ing deaths trou­bling. In com­par­ing the pros and cons of all the vac­cines, the pan­elists agreed that side ef­fects from the Pfiz­er and Mod­er­na vac­cines weren’t as se­ri­ous — and that sup­plies now are plen­ti­ful.

Nor is J&J still con­sid­ered a one-and-done vac­cine, sev­er­al ad­vis­ers not­ed. The sin­gle-dose op­tion didn’t prove quite as pro­tec­tive as two dos­es of the Pfiz­er and Mod­er­na vac­cines. Plus, with ex­tra-con­ta­gious virus mu­tants now spread­ing, boost­er dos­es now are rec­om­mend­ed.

For J&J re­cip­i­ents, a boost­er is rec­om­mend­ed at least two months af­ter vac­ci­na­tion. U.S. health of­fi­cials had pre­vi­ous­ly okayed mix­ing vac­cines for boost­er shots.

Sev­er­al coun­tries, in­clud­ing Cana­da, al­ready have poli­cies that give pref­er­ence to the Pfiz­er and Mod­er­na vac­cines. But J&J told the com­mit­tee its vac­cine still of­fers strong pro­tec­tion and is a crit­i­cal op­tion es­pe­cial­ly in parts of the world with­out plen­ti­ful vac­cine sup­plies or for peo­ple who don’t want a two-dose shot.

While blood clots are rare, “un­for­tu­nate­ly cas­es of COVID-19 are not,” J&J’s Dr. Pen­ny Heaton said.

The U.S. is for­tu­nate in its vac­cine avail­abil­i­ty and Thurs­day’s ac­tion shouldn’t dis­cour­age use of J&J’s vac­cine in places around the world where it’s need­ed, said CDC ad­vis­er Dr. Matthew Da­ley of Kaiser Per­ma­nente Col­orado.

The FDA al­so warned this week that an­oth­er dose of the J&J vac­cine shouldn’t be giv­en to any­one who de­vel­oped a clot fol­low­ing ei­ther a J&J or As­traZeneca shot.

The com­mit­tee al­so heard some of the first da­ta on re­port­ed side ef­fects of Pfiz­er vac­ci­na­tions in younger chil­dren. Ear­ly last month, the CDC rec­om­mend­ed a two-dose se­ries for that age group, and more than 7 mil­lion dos­es have been giv­en so far. But few prob­lems have been re­port­ed. Of the 80 re­port­ed cas­es of se­ri­ous side ef­fects, about 10 in­volved a form of in­flam­ma­tion that has been seen in male teens and young adults.