Vaccine-derived poliovirus type 2 (cVDPV2) detected in environmental surveillance in Eastern Region, Ghana – Sherrif Awiagah & Solomon Awiagah

On the 16^th of September,2024, the Ministry of Health, Ghana in a statement (see attached) signed by the minister, Dr. Bernard Okoe Boye notified the public about a confirmed case of poliovirus type 2 from environmental samples in the Eastern Region. We report in this publication what this means for the general public.

Poliovirus

The polio virus is the causative agent of the highly infectious disease known as poliomyelitis (in short, polio). It mainly causes disease in young children and can lead to lifelong paralysis (when muscles can no longer move). It can even cause death in some cases (2 – 10% of paralysed individuals)(1). As of October 2023, there were only two countries where polio remains endemic, Pakistan and Afghanistan(2). Through vaccination efforts, surveillance activities and epidemiological investigations, most countries have been declared polio free. The WHO has certified five regions including Africa, polio-free. However, the virus still poses a threat especially in areas with low vaccine coverage. The virus is transmitted from person-to-person through fecal-oral route and less frequently through contaminated food and water. It multiplies in the intestines and eventually invade the nervous system, where it causes the paralytic effect.

The specific type of virus found in Koforidua is known as the Vaccine-derived Poliovirus type 2 (cVDPV2). Vaccine-derived poliovirus type 2 (cVDPV2) is a strain of poliovirus that’s mutated from the weakened form of poliovirus in the oral polio vaccine (OPV). The OPV is a live vaccine which allows the weakened virus to replicate in the intestines and build up antibodies and develop immunity (2) .However, in rare cases, the OPV can genetically change and spread in communities that aren’t fully vaccinated against polio. This can happen when(1,3):

• There isn’t enough vaccination against polio
• The weakened strain spreads to under-immunized populations
• People with certain immunodeficiency disorders shed the virus for long periods of time

cVDPV2 is classified as such when it’s detected in at least two different sources that are genetically linked and at least two months apart(1,3).

The novel oral poliovirus vaccine type 2 (nOPV2) has been engineered to increase the genetic stability of the OPV, which may reduce the risk of cVDPV2 outbreaks(4).

However, the isolation been reported now is from an environmental sample. Vaccine-derived poliovirus type 2 (cVDPV2) has been detected in environmental surveillance sites around the world including Ghana (2019, which brought Ghana’s polio free status to a stop (5) & now), UK (2022)(6), Burundi (2023)(7), Israel (2022)(8). Environmental surveillance has allowed for the early detection of poliovirus circulation and importation. The number of areas reporting the isolation of cVDPV from environmental surveillance has increased since the start of the pandemic. The virus was detected in sewage water during routine investigations by NMIMR. This does not mean people are sick yet, but the finding shows the virus is present in the environment. The Ministry of Health-Accra, Ghana, has declared this a Public Health Emergency, meaning the situation requires immediate and coordinated response to prevent wider spread of the virus.

What actions are being taken?

The Ministry of health in collaboration with Ghana Health Service, and international organisations has initiated immediate actions to prevent the spread of the virus. These include detailed field investigations to identify the source of the virus, assessment of its potential geographical threat, and risk evaluation of human transmission. Enhanced surveillance and community engagement efforts are also underway to prevent any spread of the virus.

While the above measures are being implemented, the Ministry of health strongly urges people to observe stringent sanitation and hygiene practices such as:

• Regular hand washing with soap under safe running water after using the toilet, before eating or before feeding your baby and after playing outdoor games (children)
• Regular cleaning of contaminated surfaces
• Proper disposal of human waste
• Avoid open defecation

One of the most effective ways to prevent the spread of poliovirus is vaccination. Parents and caregivers are reminded to complete the vaccination schedules for their infants to ensure their protection.

This discovery is a reminder that although polio is rare today, it is still a threat. Through the collective efforts of individuals, communities and institutions, the return of this dangerous disease can be prevented. Stay safe, adhere to health guidelines and let’s work together to protect our communities from polio.

For further reading

1. WHO. https://www.who.int/emergencies/disease-outbreak-news/item/2024.2024. Circulating vaccine-derived poliovirus type 2 (cVDPV2) – Indonesia.
2. WHO. https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON480.2023. Circulating vaccine-derived poliovirus type 2 (cVDPV2) – United Republic of Tanzania.
3. CDC. https://www.cdc.gov/vaccines/vpd/polio/hcp/vaccine-derived-poliovirus-faq.html.2022. Vaccine-Derived Poliovirus.
4. Ochoge M, Futa AC, Umesi A, Affleck L, Kotei L, Daffeh B, et al. Safety of the novel oral poliovirus vaccine type 2 (nOPV2) in infants and young children aged 1 to <5 years and lot-to-lot consistency of the immune response to nOPV2 in infants in The Gambia: a phase 3, double-blind, randomised controlled trial. The Lancet [Internet]. 2024 Mar 23;403(10432):1164–75. Available from: https://doi.org/10.1016/S0140-6736(23)02844-1.
5. Odoom JK, Obodai E, Boateng G, Diamenu S, Attiku K, Avevor P, et al. Detection of vaccine-derived poliovirus circulation by environmental surveillance in the absence of clinical cases. Hum Vaccin Immunother. 2021 Jul 3;17(7):2117–24.
6. Klapsa D, Wilton T, Zealand A, Bujaki E, Saxentoff E, Troman C, et al. Sustained detection of type 2 poliovirus in London sewage between February and July, 2022, by enhanced environmental surveillance. The Lancet. 2022 Oct;400(10362):1531–8.
7. WHO. https://www.who.int/emergencies/disease-outbreak-news/item/2023.2023. Circulating vaccine-derived poliovirus type 2 – Burundi.
8. Zuckerman NS, Bar-Or I, Sofer D, Bucris E, Morad H, Shulman LM, et al. Emergence of genetically linked vaccine-originated poliovirus type 2 in the absence of oral polio vaccine, Jerusalem, April to July 2022. Eurosurveillance. 2022 Sep 15;27(37).