Study finds flu vaccine effective in elderly during widespread outbreaks
Seasonal influenza vaccination is significantly effective in elderly, community-dwelling populations during seasons in which flu activity is widespread, according to a meta-analysis yesterday in Lancet Infectious Diseases.
Dutch researchers analyzed 35 studies containing 49 datasets of information from 15 countries and 9 flu seasons. They reduced confounding bias and improved accuracy by including only studies that used a test-negative, case-control design.
All flu cases were lab-confirmed in a primary care setting or during hospital admission. The team excluded studies that didn't use polymerase chain reaction for confirmation and those that obtained specimens more than 7 days after symptom onset.
They evaluated vaccine effectiveness according to antigenic match and epidemic conditions, which were defined as influenza cases in multiple countries, the study said.
The meta-analysis found that seasonal flu vaccination was significantly effective against lab-confirmed flu in the elderly during regional or widespread outbreaks, regardless of whether the vaccine was a good match to circulating strains. The vaccine was also significantly effective during sporadic flu activity, but only when it was a good match.
Vaccination was found to be not significantly effective in the elderly during local flu virus activity—ie, limited to one country—regardless of match to circulating strains, the authors said.
In a related commentary, Michael L. Jackson, PhD, MPH, of the Group Health Research Institute in Seattle commends the study for its rigorous methods while noting that the results may not entirely account for variability in different vaccines used in the 15 countries, dominant virus types and subtypes across seasons and geography, and the measurement of vaccine antigenic match.
Both the authors of the meta-analysis and Jackson conclude that seasonal flu vaccination should be recommended in the elderly and mention an ongoing need for meta-analyses and robust prospective vaccine effectiveness studies in diverse populations.
Nov 6 Lancet Infect Dis article
Nov 6 Lancet Infect Dis commentary
Saudis announce 2 more MERS cases, education campaign
Saudi Arabia's Ministry of Health (MOH) has issued yet another update to its recent flurry of MERS-CoV case reports, adding two more cases today, bringing the country's total to 798.
The new case-patients are a 45-year-old man from Riyadh and a 49-year-old man from Jeddah. Neither is a healthcare worker and neither had known contact with a suspected or confirmed MERS-CoV (Middle East respiratory syndrome coronavirus) patient in the hospital.
The Riyadh man, who had preexisting disease, did have contact with a MERS patient in the community. The Jeddah man is currently listed as being in critical condition and his animal exposure status is listed as "under investigation" in the report.
Also, the MOH in a press release today announced the launch of a public information campaign in the city of Taif, site of numerous cases in the country's recent MERS-CoV spike. Medical professionals at various locations will educate the public on the "crucial role of the community in preventing the spread of the disease," says the release.
The campaign will focus on alerting individuals to the importance of avoiding unprotected exposures to camels and to properly boiling/cooking camel milk and meat before ingestion. The release said that, of 38 Saudi MERS cases since Sep 5, nearly a third have had camel contact.
Nov 7 MOH update
Nov 7 MOH press release
In related news, the World Health Organization (WHO) today confirmed 12 additional MERS cases that Saudi Arabia reported from Oct 27 to Oct 30, as well as 3 deaths from Oct 4 to Oct 24. The agency said that household and healthcare contacts for the active cases are being traced.
The WHO does not specify information on each case-patient but says 11 (92%) had comorbidities, none had traveled or performed Umrah or Hajj in the 14 days prior to illness, and only 1 had a history of contact with animals and consumption of raw camel products.
Locations of the 12 cases are Riyadh (5), Taif (4), Hafar Al-Batin (1), Al Jawf (1), and Mecca (1). Seven patients came into contact with MERS-CoV patients in the community, and two, including a healthcare worker, were in hospitals with MERS patients although they had no reported contact.
The WHO's global total for lab-confirmed cases stands at 909 with "at least 331 related deaths."
Nov 7 WHO update
Study finds no transmission of MERS to health workers
Although MERS-CoV certainly holds the potential for transmission and several reports of such have been published, a study yesterday in Emerging Infectious Diseases (EID) identified no evidence of infection in hospital healthcare workers (HCWs) who had contact with an infected patient.
The index patient was hospitalized in June 2012 after a 7-day history of fever, cough, sputum expectoration, and shortness of breath. Airborne-transmission precautions were taken for 2 days, followed by droplet precautions for 2 days and then contact precautions. The patient died on day 11.
The authors, from Saudi Arabia and the US Centers for Disease Control and Prevention, tested blood specimens from 48 HCWs who had known contact with the patient and from a roughly equal number of control HCWs 4 months after the patient's death.
The samples from the contact group and controls were all found to be negative for MERS-CoV by HKU5.2N nucleocapsid enzyme immunoassay. Thirteen randomly selected serum specimens from the test group were likewise negative on immunofluorescence assay.
Nov 6 EID study
Iranian MERS cluster showed evidence of person-to-person spread
Another MERS study in EID published Nov 5 involved a cluster of five cases in Iran from May to July 2014 and demonstrated likely person-to-person spread in four of the patients.
The authors, from Tehran University and the Iranian Center for Communicable Disease Control, tested 1,800 patients with respiratory illness from January 2013 through August 2014 for MERS-CoV.
The cluster, which occurred in Kerman province, involved a woman who had contact with an ill friend who had traveled to Saudi Arabia but had incomplete testing for MERS-CoV. It also included the woman's sister, a nurse and a physician who had contact with the initial case in the intensive care unit, and a patient at the hospital who was admitted after the two women were gone (the first patient died, and her sister was discharged).
None of the cluster patients had traveled or had contact with animals in the 14 days prior to illness onset.
The authors say person-to-person transmission is likely responsible for the first four cases but that the route of transmission for the last is unclear. They conclude, "Future research should focus on clarifying routes of transmission for this virus, including the possibility of transmission from persons with subclinical infection."
Nov 5 EID study