WHO & Regional Offices [to 8 Sep 2018]
Launch of new global estimates on levels of physical activity in adults
5 September 2018 | News Release
Protecting women in Solomon Islands from cervical cancer
4 September 2018 – Feature story
WHO airlifts over 500 tons of essential medicines and medical supplies to Yemen
3 September 2018 | News Release
Weekly Epidemiological Record, 7 September 2018, vol. 93, 36 (pp. 457–476)
:: Dengue vaccine: WHO position paper – September 2018
The live attenuated dengue vaccine CYD-TDV has been shown in clinical trials to be efficacious and safe in persons who have had a dengue virus infection in the past (seropositive individuals), but carries an increased risk of severe dengue in those who experience their first
natural dengue infection after vaccination (seronegative individuals). Countries should consider introduction of the dengue vaccine CYD-TDV only if the minimization of risk among seronegative individuals can be assured.62
For countries considering vaccination as part of their dengue control programme, pre-vaccination screening is the recommended strategy. 63 With this strategy, only persons with evidence of a past dengue infection would be vaccinated (based on an antibody test, or on a documented laboratory confirmed dengue infection in the past). If pre-vaccination screening is not feasible, vaccination without individual screening could be considered in areas with recent documentation of seroprevalence rates of at least 80% by age 9 years.
Screening tests would need to be highly specific to avoid vaccinating truly seronegative persons and to have high sensitivity to ensure that a high proportion of seropositive persons are vaccinated. Conventional serological testing for dengue virus IgG (e.g. dengue IgG ELISA)
is available in most dengue endemic countries, and could be used to identify persons who have had a past dengue infection. However, such laboratory-based assays do not provide results at the point of care. Point-of-care tests, i.e. RDTs, would facilitate the implementation of the pre-vaccination screening strategy, but to date none have been validated or licensed specifically for the detection of past dengue infection. Use of currently available IgG-containing RDTs – despite their lower sensitivity for detection of past dengue infection compared with conventional dengue IgG ELISA – could be considered in high transmission settings until better RDTs for determining serostatus become available.
No screening test is likely to be 100% specific due to potential cross-reactivity with other flaviviruses. In settings with high dengue seroprevalence, a test with lower specificity might be acceptable as the proportion of seronegative individuals incorrectly vaccinated would be low. A pre-vaccination screening strategy may also be considered in low-to-moderate transmission settings. In settings with low seroprevalence a test with high specificity is needed. Given the limitations regarding specificity, some seronegative individuals may be vaccinated because of a false positive test result. Furthermore, as vaccine-induced protection against dengue in seropositive individuals is high but not complete, breakthrough disease will occur in some seropositive vaccinees. These limitations will need to be communicated to populations offered vaccination.
Decisions about implementing a pre-vaccination screening strategy with the currently available tests will require careful assessment at the country level, including consideration of the sensitivity and specificity of available tests and of local priorities, dengue epidemiology, country-specific dengue hospitalization rates, and affordability of both CYD-TDV and screening tests.
Decisions about implementing a seroprevalence criterion-based vaccination strategy without individual screening in areas with documented seroprevalence rates of at least 80% at age 9 years will require population serosurveys at high resolution, i.e. at district and sub-district level. Careful assessment is required with regard to the feasibility and cost of population seroprevalence studies. Communication needs to ensure appropriate and full disclosure of the risks of vaccination of persons with unknown serostatus.
Vaccination should be considered as part of an integrated dengue prevention and control strategy. There is an ongoing need to adhere to other disease preventive measures such as well-executed and sustained vector control. Individuals, whether vaccinated or not, should
seek prompt medical care in if dengue-like symptoms occur. Vaccinated patients should continue to be offered the best evidence-based clinical care for all patients with dengue…
62 Evidence to recommendation Table 1: Consideration of Dengue Vaccine. Geneva:
World Health Organization; 2018 – http://www.who.int/immunization/policy/position_
63 Evidence to recommendation Table 2: Seroprevalence and screening and vaccination
strategy. Geneva: World Health Organization; 2018 – http://www.who.int/immunization/
WHO Regional Offices
Selected Press Releases, Announcements
WHO African Region AFRO
Selected Featured News
:: South Sudan intensifies Ebola preparedness in response to the outbreak in Democratic Republic of Congo 07 September 2018
:: WHO scales up response as Borno declares another outbreak of cholera 06 September 2018
:: Uganda targets over 1,600,000 persons for Cholera vaccination campaign 05 September 2018
WHO Region of the Americas PAHO
No new digest content identified.
WHO South-East Asia Region SEARO
:: Countries in WHO South-East Asia to intensify efforts to control dengue, eliminate malaria
:: Strengthen emergency medical teams for better response to disasters: WHO
:: Dr Poonam Khetrapal Singh unanimously nominated for second term as Regional Director WHO South-East Asia
:: Countries in WHO South-East Asia Region resolve to make essential medical products accessible, affordable to all
WHO European Region EURO
:: WHO launches a cutting-edge package to scale up risk communication capacity in the European Region in 5 steps 06-09-2018
:: Confirmed case of MERS-CoV in United Kingdom 03-09-2018
WHO Eastern Mediterranean Region EMRO
:: Generous donation from Japan boosts public health services in Syria 3 September 2018
:: WHO airlifts over 500 tons of essential medicines and medical supplies to Yemen 3 September 2018
:: Palestinian casualties of Gaza demonstrations 3 September 2018
: 14 million children in Afghanistan to be immunized against measles 1 September 2018