Vaxcyte shares surge as pneumococcal vaccine succeeds in late-stage trial

By Siddhi Mahatole

Oct 5 (Reuters) - Vaxcyte PCVX.O said on Monday its experimental pneumococcal vaccine generated immune responses comparable to rival vaccines in a late-stage study, sending its shares up 57% in morning trading.

Here are key details:

• Pneumococcal disease is caused by bacteria that can lead to pneumonia, meningitis and bloodstream infections, with older adults particularly at risk

• The vaccine, VAX-31, produced immune responses that were at least comparable to Pfizer's PFE.N Prevnar 20 and Merck's MRK.N Capvaxive against the 28 bacterial strains, or serotypes, shared with one or both rival vaccines

• It also produced stronger immune responses against three strains unique to VAX-31 and against strain 20B, the company said

• The vaccine had a consistent safety profile across the age groups studied, with no serious adverse events considered related to the vaccines

• Jefferies analyst Roger Song said the results hit the "blue-sky" case, with VAX-31 poised to take significant share of the $3 billion to $6 billion-plus adult vaccine market

• In separate comparisons, VAX-31 met the study's benchmark for all 20 strains it shares with Prevnar 20 and for 17 of 19 shared with Capvaxive

• For the other two strains shared with Capvaxive, VAX-31 missed the study's stricter benchmark but met a historical threshold

• Leerink Partners analyst David Risinger said VAX-31's miss against Merck's Capvaxive on serotype 3 reflected a tougher trial standard and was unlikely to have regulatory significance

• Vaxcyte expects results from two other late-stage trials in the first half of 2027 and plans to submit a US marketing application in the first half of 2028