WHO seeks vaccine viruses based on recent H5N1, H5N8 strains
As part of its ongoing influenza pandemic preparedness efforts, the World Health Organization (WHO) is calling for the development of candidate vaccine viruses based on H5N1 viruses from recent human cases in Egypt and an H5N8 virus that was found in a wild bird in Washington state in December.
In its Weekly Epidemiological Record, the WHO said recent H5N1 isolates from Egypt have accumulated enough mutations so that a vaccine based on a 2010 Egyptian H5N1 strain does not react very strongly with them, on the basis of tests in ferrets. The implication is that if the H5N1 strain now circulating in Egypt evolved into a pandemic virus, a vaccine based on the 2010 strain wouldn't work very well against it.
The selection and development of candidate vaccine viruses is the first step toward vaccine production in case of a flu pandemic, but the steps do not imply a recommendation for actually starting production, the WHO noted. Governments can consider using the candidate viruses to make pilot batches of vaccine for clinical trials, depending on their perception of pandemic risk.
Concerning recent H5N8 viruses, the WHO said their hemagglutinin (H) component belongs to the same clade (18.104.22.168) as that of recent H5N6 and H5N8 viruses from China and H5N6 viruses from Vietnam and Laos. A candidate vaccine virus for an H5N6 virus from China is now in development, it said.
But in ferret tests, that candidate H5N6 vaccine strain did not react well with recent H5N8 and H5N2 isolates from the United States. Consequently the WHO said it is recommending development of a new candidate vaccine virus based on the H5N8 virus found in a captive gyrfalcon in Washington in December.
Closely related H5N8 and H5N2 viruses have surfaced in a number of wild birds and poultry flocks in the United States recently. No human cases of H5N8 infection have been reported, but three human H5N6 cases have been reported in China.
Mar 20 Wkly Epidemiol Rec article
WHO adds info on 15 Saudi MERS cases
Of 15 recent MERS-CoV cases in Saudi Arabia detailed in an update by the WHO today, 11 involved serious infections and 6 involved potential exposure to the virus in healthcare settings.
The patients, 10 of whom are from Riyadh, developed symptoms from Feb 23 to Mar 7. They range in age from 30 to 72, and eight are men. Eleven had pre-existing disease, and 12 are Saudi nationals. Six are listed in critical condition, four are in stable condition, and five died.
Six patients had potential MERS-CoV (Middle East respiratory syndrome coronavirus) exposure in hospitals, and one had contact with a MERS patient in the community. Two of the possibly healthcare-exposed patients were healthcare professionals.
In addition to the 10 cases in Riyadh, the cities of Buraydah, Hofuf, Kurma, Shaqra, and Unayzah had 1 case each.
Saudi Arabia has not reported a new MERS-CoV case since Mar 17, according to the country's Ministry of Health (MOH). It has, though, reported two recent deaths in previously reported cases, on Mar 18 and today, both in male Saudi nationals in Riyadh.
The death reported on Mar 18 involved a 75-year-old, and the one today involved a 63-year-old. Neither were health workers, and both had preexisting disease. The MOH on Mar 18 also reported that a 56-year-old Saudi man in Riyadh recovered from the disease, and today it noted that a 21-year-old male expatriate in Riyadh also recovered.
Mar 20 WHO statement
Mar 18 MOH update
Mar 20 MOH update
Study: Pneumococcal vaccine lowered UK incidence 56%
The incidence of invasive pneumococcal disease (IPD) dropped 56% in England and Wales after the introduction of the seven-strain pneumococcal conjugate vaccine (PCV-7) 8 years ago. But the incidence of non-vaccine-strain serotypes increased after the 13-strain version (PCV-13) was introduced, suggesting its benefits might have peaked, according to a study yesterday in The Lancet Infectious Diseases.
The researchers used a national dataset of cases of IPD that occurred before and after PCV was introduced in the country. PCV-7 was introduced in September 2006, with PCV-13 following in April 2010.
The investigators found that, from the pre-PCV baseline to the 2013-14 season, IPD incidence dropped 56%. Compared with the pre-PCV-13 baseline, IPD in 2013-14 decreased by 32%.
The latter reduction was partly attributed to an 86% reduction in serotypes covered by PCV-7 and a 69% reduction in the six additional serotypes covered by PCV-13. Non-PCV-13 serotypes, however, increased 25% from the pre-PCV-13 baseline. And from 2012-13 to 2013-14, the incidence of those serotypes rose 11% in children under 2 years old and 12% in children 2 to 4 years old.
The authors conclude, "The herd protection induced by PCV7 is continuing, and similar indirect protection is occurring from the additional serotypes covered by PCV13. There is, however, evidence of increasing invasive pneumococcal disease due to non-PCV13 serotypes, particularly in children younger than 5 years in 2014. If this increase continues, the maximum benefit of the PCV13 programme in children might already have been achieved."
Mar 19 Lancet Infect Dis study
Mar 19 Lancet Infect Dis commentary on the study