H1N1 NEWS SCAN: Canada vaccine, US flu rates stable, Tamiflu resistance, antivirals in pregnancy, strep co-infection

Apr 9, 2010

Potency decline shrinks expiration date for Canada's vaccine
Canada has shortened the expiration date on its adjuvanted H1N1 vaccine from 18 to 6 months, due to nonsafety-related declines in H1N1 antigen in some lots. Subsequent testing of the GlaxoSmithKline vaccine detected the potency issue, which has also been found in some US vaccine lots. Health officials assured the public that vaccines already administered provide sufficient protection. Relabeling guidance, expected soon, won't affect the unadjuvanted vaccine that Glaxo produced for Canada.
Apr 9 Health Canada statement

CDC sees little change in low H1N1 levels
The incidence of H1N1 flu has sunk to low levels in most of the United States, the Centers for Disease Control and Prevention (CDC) said in its weekly update. The three southeastern states about which the CDC raised the alarm a week ago—Alabama, Georgia, and South Carolina—continue to report regional flu activity. However, visits to doctors, lab-confirmed hospitalizations, and the proportion of deaths attributed to pneumonia and influenza all declined. The update covers Mar 28 through Apr 3.
Apr 9 CDCupdate

Tamiflu resistance appears in immunocompromised patients
The first cluster of oseltamivir-resistant H1N1 flu in 10 patients in Scotland appeared in a small group who were immunocompromised and persistently shed flu virus, leading to a longer-than-normal course of antivirals. The distinctive resistance mutation was limited to that group out of 1,608 who were hospitalized and did not spread beyond them. The researchers recommend that patients likely to develop resistance be monitored and they and their household contacts vaccinated when possible.
Apr 8 Euro Surveill article

No adverse effects to flu antivirals in pregnancy
Researchers from the University of Texas Southwest Medical Center report that neither oseltamivir nor amantadine/rimantadine caused any adverse events in pregnant women treated at the medical center during the H1N1 flu pandemic. The 104 women given amantadine or rimantadine and the 135 women given oseltamivir had the same rates of preterm birth, premature rupture of membranes, gestational diabetes, and preeclampsia as the 82,097 women who did not receive antivirals.
April Obstet Gynecol abstract

Rare, severe cases of H1N1 and strep co-infection
Of 8,075 patients hospitalized for H1N1 pandemic flu in California in 2009, 10 suffered severe effects from co-infection with invasive group A Streptococcus (S pyogenes). Eight needed mechanical ventilation, and 7 died. Three belonged to one family. S pneumococcus and Staphylococcus aureus have been reported with pandemic and seasonal flu, but group A strep is rare. Physicians should watch for flu complications and be sure to draw blood first and then administer antibiotics quickly.
Apr 8 Clin Infect Dis abstract

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