Progress Toward Poliovirus Containment Implementation - Worldwide, 2017-2018

Routine Childhood Vaccines Given in the First 11 Months of Life

The US Advisory Committee on Immunization Practices recommends that infants beginning at birth receive several vaccines directed against a variety of infectious diseases that currently pose threats of morbidity and mortality to infants and those around them, including the 3-dose hepatitis B (HepB) series. The first dose is due at birth. This series protects against maternal-infant transmission of the HepB virus and against exposure the rest of the infant's life. At age 2 months infants are to receive not only their second dose of HepB vaccine but also a series of vaccines directed against diphtheria, tetanus, pertussis, pneumococcus, rotavirus, poliovirus, and Haemophilus influenzae type b. At 4 months, infants are to repeat those vaccines except for the HepB vaccine. At age 6 months infants are to finish the HepB series and receive the third doses of the other vaccines received at 2 and 4 months except for the rotavirus vaccine, depending on the brand used. Also, starting at 6 months, depending on the time of year, infants are to begin a 2-dose series against influenza separated by 28 days. Each of these vaccines is due at a time when the vaccine works to protect against an immediate risk and to provide long-term protection. These vaccine-preventable diseases vary in terms of the nature of exposure, the form of the morbidity, the risk of mortality, and the ability of routine vaccination to prevent or ameliorate harm.

Progress Toward Poliovirus Containment Implementation - Worldwide, 2018-2019

Among the three wild poliovirus (WPV) types, type 2 (WPV2) was declared eradicated globally by the Global Commission for the Certification of Poliomyelitis Eradication (GCC) in 2015. Subsequently, in 2016, a global withdrawal of Sabin type 2 oral poliovirus vaccine (OPV2) from routine use, through a synchronized switch from the trivalent formulation of oral poliovirus vaccine (tOPV, containing vaccine virus types 1, 2, and 3) to the bivalent form (bOPV, containing types 1 and 3), was implemented. WPV type 3 (WPV3), last detected in 2012 (1), will possibly be declared eradicated in late 2019.* To ensure that polioviruses are not reintroduced to the human population after eradication, World Health Organization (WHO) Member States committed in 2015 to containing all polioviruses in poliovirus-essential facilities (PEFs) that are certified to meet stringent containment criteria; implementation of containment activities began that year for facilities retaining type 2 polioviruses (PV2), including type 2 oral poliovirus vaccine (OPV) materials (2). As of August 1, 2019, 26 countries have nominated 74 PEFs to retain PV2 materials. Twenty-five of these countries have established national authorities for containment (NACs), which are institutions nominated by ministries of health or equivalent bodies to be responsible for poliovirus containment certification. All designated PEFs are required to be enrolled in the certification process by December 31, 2019 (3). When GCC certifies WPV3 eradication, WPV3 and vaccine-derived poliovirus (VDPV) type 3 materials will also be required to be contained, leading to a temporary increase in the number of designated PEFs. When safer alternatives to wild and OPV/Sabin strains that do not require containment conditions are available for diagnostic and serologic testing, the number of PEFs will decrease. Facilities continuing to work with polioviruses after global eradication must minimize the risk for reintroduction into communities by adopting effective biorisk management practices.

Detection and characterization of polioviruses originating from urban sewage in Yaounde and Douala, Cameroon 2016-2017

Objective

Transmission of wild polioviruses (WPVs) and vaccine-derived polioviruses (VDPVs) have been interrupted in Cameroon since July 2014. Subsequently, Cameroon withdrew Sabin type 2 from routine immunization in April 2016. This study aimed to investigate the detection rates and overtime distribution of the types of PVs recovered from urban sewage in Cameroon.

Results

From January 2016 to December 2017, 517 sewage specimens originating from Yaounde (325 specimens) and Douala (192 specimens) were analyzed. No WPVs and VDPVs were isolated in this study. In contrast, vaccine strains of poliovirus were detected throughout the study period. Isolates Sabin types 1 and 3 were sporadically detected whereas Sabin 2 was found only from January to May 2016 both in Yaounde and Douala. The absence of Sabin 2 in sewage specimens since June 2016 indicates its rapid disappearance after withdrawal from routine immunization in April 2016. This study provides substantial support to the observation that WPV and VDPVs have been successfully eliminated in Cameroon. However, it remains essential to maintain and extend high quality environmental surveillance as long as WPV reservoirs and VDPV outbreaks are detected in Africa.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4280-6) contains supplementary material, which is available to authorized users.