Flu Scan for Mar 03, 2015

News brief

New estimate puts current flu vaccine's effectiveness a bit lower

The latest estimate of the overall effectiveness of this year's seasonal influenza vaccine puts it at just 19% (95% confidence interval [CI], 7%-29%), slightly lower than the 23% reported in mid-January, the Centers for Disease Control and Prevention (CDC) reported yesterday.

The CDC said the updated estimate of vaccine effectiveness (VE) against H3N2 viruses, the heavily dominant subtype this winter, is 18% (95% CI, 6%-29%). This is similar to the earlier estimate (22%) and confirms reduced protection against H3N2 viruses this season, the agency added.

About two thirds of circulating H3N2 viruses have not been well matched to the H3N2 in the vaccine this winter. The CDC said the estimated VE is about a third of what is expected when the vaccine is well matched to the dominant circulating viruses, though a number of other factors also influence VE.

The estimate of VE against influenza B this winter is 45% (95% CI, 14%-65%), which is similar to the VE seen when vaccine and circulating viruses are well matched, the CDC said. The earlier VE estimate did not include a separate estimate for type B because of low numbers of cases.

In practical terms, the overall VE of 19% means "the flu vaccine reduced a person’s risk of having to seek medical care at a doctor's office for flu illness by 19%," the CDC observed.
Mar 2 CDC statement on flu VE
Jan 15 CIDRAP News story on earlier CDC estimate

Fever as proxy for flu in HCWs ill-advised, study suggests

The common practice of excluding healthcare workers (HCWs) with respiratory symptoms from patient contact only if they are febrile may not be appropriate, say results of a study from the University of Chicago that found only about half of flu-positive HCWs to be febrile.

The study, published yesterday in Clinical Infectious Diseases, was carried out after influenza in a hospitalized patient was linked with an HCW who had respiratory symptoms but no fever.

Mandatory polymerase chain reaction testing of flocked nasopharyngeal swabs for influenza and other respiratory pathogens was carried out from Jan 3 through Feb 28, 2014, on 449 HCWs with respiratory symptoms (cough, sore throat, runny nose, congestion). Temperature was also measured and vaccination status reported for each.

Positive results for any respiratory pathogen were found in 243 (54%) of the HWCs, including influenza in 34 (7.6%); 7 additional HCWs were diagnosed with influenza outside of the employee-screening program, for a total of 41 with flu. Of these, only 21 (51.2%) had a history of fever or were febrile during evaluation.

Among the flu-positive HCWs, 20 had received flu vaccine, 18 had declined vaccine, and 3 had an unknown vaccine status. Although there was a trend toward fever being more common among the flu-positive HCWs who had not had flu vaccination compared with those who had, the difference was not significant (11/18 [61%] vs 9/20 [45%], P = 0.32).

The authors express the hope that their findings "can inform infection control practices and sick leave policies during the influenza season."
Mar 3 Clin Infect Dis study abstract

Two Chinese provinces report new H7N9 cases

Two of China's provinces—Anhui and Guangdong—reported new H7N9 avian influenza infections today, according to official reports translated and posted by FluTrackers, and infectious disease news message board.

Anhui province's patient is a 50-year-old man from Chaohu who had contact with live poultry before he got sick. His H7N9 infection was confirmed yesterday, and he is being treated in the hospital.

Guangdong province's latest case-patient is a 36-year-old woman from Chaozhou whose illness was confirmed yesterday. She is hospitalized in critical condition.

FluTrackers said two Mar 1 H7N9 cases from Zhejiang province reported yesterday by Macau's health department, both involving children, have been retracted. Given that development, the new cases reported today keep the global total from H7N9 at 622, according to a case list maintained by FluTrackers.
Mar 3 FluTrackers thread on Anhui case
Mar 3 FluTrackers thread on Guangdong case
FluTrackers H7N9 case list

H5N1 strikes poultry in Nigeria again

A series of H5N1 avian influenza outbreaks in Nigeria was renewed with a recent hit on a layer chicken farm in Ogun state in the far southwestern part of the country, Nigerian authorities have told the World Organization for Animal Health (OIE).

The Mar 2 report said the virus killed 2,148 of 30,046 chickens on a cluster of farms in the Ado-Odo settlement, prompting culling of the rest of the birds to stop the virus's spread. The outbreak started Feb 14.

The source of the virus was unknown. In addition to culling the chickens, authorities have quarantined and disinfected the outbreak site and restricted poultry movements in the area, the report said.

H5N1 resurfaced in Nigeria in late December, after an absence of reported outbreaks for several years, according to OIE reports.
Mar 2 OIE report from Nigeria

News Scan for Mar 03, 2015

News brief

Saudis report another MERS case, raising March total to 12

Saudi Arabia reported another MERS case today, raising the count for the first 3 days of March to a dozen, 11 of which occurred in Riyadh.

The case involves a 70-year-old Saudi woman in Riyadh who has a preexisting disease and is in critical condition, the Ministry of Health (MOH) reported. She is not a healthcare worker and has no history of recent exposure to other MERS-CoV (Middle East respiratory syndrome coronavirus) cases, but possible animal exposure is under investigation.

The new case increased the MOH's cumulative MERS tally to 932 cases, including 400 deaths, 503 recoveries, and 29 patients still under treatment. The latter figure includes two patients on home isolation.

The 12 cases reported so far this month follow 75 cases reported in Saudi Arabia in February, but just 20 cases in January.

February marked the third most active month of the past 11 months for MERS in Saudi Arabia, according to an analysis posted today on ProMED-mail, the reporting service of the International Society for Infectious Diseases.

ProMED Deputy Editor Marjorie P. Pollack wrote that data on the MOH site show that 209 cases were reported in May 2014, during a springtime MERS surge, and that partial data for April 2014 show 177 cases. In October there were 36 cases, but all other months since last spring were marked by fewer than 30 cases, according to Pollack.

She noted that 22 of the 86 cases reported from Feb 1 through Mar 2 involved contact with MERS in a healthcare setting, pointing to ongoing transmission in hospitals and clinics. In addition, 10 of the 86 patients were exposed to camels or camel products in the 2 weeks before their illness.
Mar 3 MOH statement on new case
Mar 3 ProMED-mail post on MERS cases

Study: HPV vaccination programs cut infections, anogenital warts

The long-term population-level effects of widespread female vaccination programs for human papillomavirus (HPV), begun in 2007, are promising, cutting infection rates by up to 68% and anogenital warts up to 61%, but continued surveillance for waning efficacy remains important, according to a meta-analysis published yesterday in The Lancet Infectious Diseases.

The international group of authors, from Quebec and elsewhere, searched for HPV articles published between Jan 1, 2007, and Feb 28, 2014, that analyzed changes in incidence or prevalence of HPV before and after HPV vaccination programs were implemented.

The analysis included 20 studies from nine high-income countries that use the quadrivalent vaccine targeting HPV types 16 and 18, which are associated with 70% to 80% of cervical cancers, and types 6 and 11, associated with 85% to 95% of anogenital warts. The studies involved 16,600 women.

In countries with female vaccination coverage of at least 50%, the overall prevalence of HPV types 16 and 18 infections in girls aged 13 to 19 years decreased significantly (68%) from pre- to post-vaccination years (relative risk [RR], 0.32; 95% confidence interval [CI], 0.19-0.52), and the incidence of anogenital warts dropped by 61% (RR, 0.39; 95% CI, 0.22-0.71).

Significant reductions were likewise seen for HPV types 31, 33, and 45 in the same age-group (RR, 0.72; 95% CI, 0.54-0.96), suggesting cross-protection, according to the authors.

The incidence of anogenital warts in boys younger than 20 years was significantly reduced (RR, 0.66; 95% CI, 0.47-0.91), as it was in women 20 to 39 years (RR, 0.68; 95% CI, 0.51-0.89), providing strong evidence of both cross-protection and herd immunity.

Countries with HPV vaccine coverage rates below 50% also saw significant reductions in the rates of HPV types 16 and 18 infection in girls younger than 20 (RR, 0.50, 95% CI, 0.34-0.74) as well as in the incidence of anogenital warts (RR, 0.86; 95% CI, 0.79-0.94), but with no evidence of cross-protection or herd protection.

The authors of an accompanying commentary find it "striking" that the greatest effect of HPV vaccine was apparent in countries with school-based vaccination programs (Australia, New Zealand, and the United Kingdom), a finding corroborated in other studies.
Mar 3 Lancet Infect Dis study abstract
Accompanying commentary