Flu Scan for May 05, 2015

News brief

Anhui province reports China's 2nd H7N9 case this month

A new case of H7N9 avian flu has been reported from China, this one in a 3-year-old boy from Huaibei City, according to machine-translated notices from provincial health officials posted yesterday on FluTrackers, an infectious disease message board.

The child, who is reportedly in stable condition with mild symptoms, had contact with live poultry before his Apr 27 disease onset. He received outpatient treatment.

Huaibei is in northern Anhui province, which lies in east-central China. The new case is the second reported in the country so far in May.

The global total for H7N9 cases stands at 660, according to a case list maintained by FluTrackers. Cases have slowed considerably since the beginning of 2015, and experts claim the third wave of H7N9 may be over.
May 4 FluTrackers thread
FluTrackers H7N9 case list
May 1 CIDRAP News scan regarding slowing of cases

Study: Influenza overshadowed by bacterial diseases in clinical diagnosis

Influenza is diagnosed clinically in only 29% of patients with laboratory-confirmed flu in medical setting, with bacterial diseases apparently given preferential consideration, say findings of a study published yesterday in the Journal of Infectious Diseases.

The authors, from Wake Forest School of Medicine, evaluated 504 case-patients who were admitted to the hospital or seen in the emergency department with fever or respiratory symptoms from 2009 to 2013 and were later confirmed as having influenza on the basis of viral culture and/or polymerase chain reaction testing.

Influenza was the clinical diagnosis in only 29% of the group, including 56% of the 236 with high-risk conditions. A clinical diagnosis of influenza was defined as a discharge diagnosis of flu, a prescription for a neuraminidase inhibitor, or a positive rapid flu test.

Predictors of flu on clinical diagnosis included race/ethnicity, insurance status, year, being hospitalized, having high-risk conditions, and not having a bacterial diagnosis. The authors conclude, "Being diagnosed with a bacterial infection reduced the odds of an influenza diagnosis over 3-fold for all patients and for patients with high risk conditions."
May 4 J Infect Dis abstract

News Scan for May 05, 2015

News brief

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