Said Arabia reports 3rd MERS case this month

A 39-year-old man is the latest addition to Saudi Arabia's MERS-CoV case count. His illness was reported today by the Saudi Ministry of Health (MOH).

The case-patient is a Saudi national from the city of Hofuf in the Eastern province bordering the Persian Gulf. He reportedly had contact with suspected or confirmed MERS-CoV (Middle East respiratory syndrome) cases in the community or hospital setting, but no other demographic or exposure details were given.

His case brings the cumulative count in Saudi Arabia since June 2012 to 984, with 428 deaths, 552 recoveries, and 4 active cases. His case is the third so far this month in the country, compared with 8 in April, 53 in March, and 75 in February.
May 5 MOH update

Studies note pertussis vaccine protection in infants, waning effect in teens

Two studies yesterday by Centers for Disease Control and Prevention (CDC) investigators noted the effectiveness of the pertussis vaccine in preventing death and hospitalization in infants but also the waning effectiveness of the pertussis-containing Tdap vaccine over time among adolescents in a 2012 Washington state pertussis (whooping cough) outbreak.

Both studies appeared in the journal Pediatrics.

In the first study, CDC researchers analyzed data on 45,404 US pertussis cases in infants from 1991 through 2008, including 258 fatal cases. They used multivariable logistic regression to estimate the effect of one or more doses of pertussis vaccine on outcomes and to assess factors related to death from pertussis.

Among infants 42 days and older (ie, age-eligible for pertussis vaccination), receiving at least one dose of vaccine was associated with a 72% decrease in the estimated relative risk of fatal pertussis  (adjusted odds ratio [aOR] of 0.28). Vaccine also protected against hospitalization (aOR, 0.69) and pneumonia (aOR, 0.80).

In assessing factors associated with fatal pertussis, the authors found the risk to be elevated in Hispanics and Native Americans  (aOR of 2.28 and 5.15, respectively). Antibiotic treatment was associated with a lower risk of death (aOR, 0.28).

In infants younger than 42 days, the risk of death was again elevated in Hispanics and lower with antibiotic use.

The authors concluded that providers "should ensure vaccination as early as 6 weeks of age during pertussis outbreaks and provide early recommended antibiotic treatment."
May 4 Pediatrics abstract on infant protection

In the Washington study, CDC researchers teamed with those from the Washington State Department of Health on a case-control study during the state's pertussis epidemic in 2012 among adolescents born from 1993 through 2000.

All pertussis cases from Jan 1 through Jun 30, 2012, in seven counties were included, with each case matched with three controls. Participants were classified by whether they had received a mix of the whole-cell and the acellular vaccine, known as Tdap (tetanus, diphtheria, and acellular pertussis, adsorbed), or just Tdap alone. Those born from 1998 on would have received Tdap only.

Among adolescents who received acellular vaccines exclusively (450 cases and 1,246 controls), overall Tdap vaccine effectiveness (VE) was 63.9%, but it varied widely from the last date of vaccination. VE within 1 year of vaccination was 73%, but at 2 to 4 years post-vaccination, it declined to 34%.

The authors conclude, "Lack of long-term protection after vaccination is likely contributing to increases in pertussis among adolescents."
May 4 Pediatrics abstract on waning Tdap effectiveness