Novavax Falls as Respiratory Vaccine Results Don't Impress

  • Company was Tuesday's worst performer on Nasdaq Biotech Index
  • Infant antibody levels may not be high enough, Piper says

Novavax Inc. was Tuesday’s worst performer on the Nasdaq Biotechnology Index as data from a mid-stage trial on the company’s respiratory vaccine failed to impress investors.

Shares of the vaccine maker fell 21 percent to $6.41 at the close in New York, the biggest decline since May 2009. While the 143-member Nasdaq Biotechnology Index has fallen for the past week and tumbled 6 percent on Monday, those losses slowed Tuesday, with the index down less than 1 percent.

The company released trial results Tuesday showing that mothers vaccinated for respiratory syncytial virus, a leading cause of hospitalization for U.S. infants, could pass on protection to their newborns. While those results helped garner funding from the Bill & Melinda Gates Foundation, the effect was too muted to attract demand from doctors and patients for the vaccine to protect children, Piper Jaffray & Co. said.

Novavax studied 50 pregnant women in their third trimester and found that those who received the vaccine had increased levels of antibodies, while those on a placebo had no significant change. Those results extended to their babies, with elevated levels remaining in their bloodstreams long enough to provide a few months of protection after birth, Novavax said. The vaccine was found to be safe and well tolerated, the company said.

While the data show "proof-of-concept," the concentration of antibodies in the blood seemed low, particularly for the RSV/B strain of the virus, Piper analyst Edward Tenthoff said in a research note Tuesday. The average was 759 micrograms per milliliter for RSV/A and 481 micrograms per milliliter for RSV/B.

Tenthoff said he remains overweight the stock and bullish on the vaccine’s potential for the elderly.

RSV is the most common cause of lower respiratory tract infections such as pneumonia in infants and young children worldwide. While there’s no currently approved vaccine for the ailment, pediatricians can prescribe AstraZeneca Plc’s drug Synagisfor children with high risk of infection. GlaxoSmithKline Plc is studyinga vaccine to prevent the disease in children.

Before it's here, it's on the Bloomberg Terminal. LEARN MORE