Quick Links #6: Expanded Age Groups for Vaccination – Do we have the evidence to evaluate communication risk?

Below you'll find a brief list of just some of the polio communication resources related to expanded age groups for polio vaccination from The Communication Initiative for Pakistan and Afghanistan.

Hi Everyone,

This Quick Links looks at research on the immunological impact of, and arguments for, expanding the age of children to be immunised against polio.  Research on the impact of expanded age groups for polio vaccination (EAG) suggests that while this can offer some benefit in some contexts such as preventive measures in high risk areas prior to type-specific surges, overall, it offers limited benefit compared to other interventions such as improving the speed of vaccination response and higher quality SIAs targeted at hard to reach populations.  Any intervention that provides limited benefit and only in some contexts, needs to be carefully evaluated against risks.  Considering episodes like the public panic and viral social media misinformation that led to the large spike in refusals related to an EAG campaign in Khyber Pakhtunkhwa in April 2019, the risks in certain contexts can be high, particularly on the communication side.  And yet, the communication risks are poorly understood and hardly mentioned in the literature we’ve found on EAG.  

Below are three analyses pointing out the marginal impact of EAG on immunity when compared with other interventions.  If any of you know of other works that speak to the communication risks of EAG and/or communication strategies that have been successful in ameliorating risks, please share them as they would be enormously helpful in assessing when, or if, EAG can be a useful tool in the eradication end game.

The role of older children and adults in wild poliovirus transmission

The incidence of poliomyelitis has dropped precipitously over the last decade. However, persistent transmission in three countries and outbreaks elsewhere challenge the end-2014 eradication target. The Global Polio Eradication Initiative is considering expanding the age range of vaccination campaigns even in the absence of adult cases, because of concerns about imperfect, waning intestinal immunity. The success of this approach will depend on the contribution to transmission by older ages, which we estimated during two large outbreaks affecting adults. Their contribution was found to depend on the setting, but there was no evidence for imperfect immunity contributing to the transmission of infection. Even small gains in the speed of vaccination response were found to have substantially greater benefit compared with expanded age range campaigns.

Quantifying the Impact of Expanded Age Group Campaigns for Polio Eradication

This paper found that EAG campaigns would not significantly improve prospects for polio eradication; the probability of elimination increased by 8% (from 24% at baseline to 32%) when expanding three annual SIAs to 5–14 year old children and by 18% when expanding all six annual SIAs. In contrast, expanding only two of the annual SIAs to target hard-to-reach populations at modest vaccination coverage—representing less than one tenth of additional vaccinations required for the six SIA EAG scenario—increased the probability of elimination by 55%. Implementation of EAG campaigns in polio endemic regions would not improve prospects for eradication. In endemic areas, vaccination campaigns which do not target missed populations will not benefit polio eradication efforts.

The potential impact of expanding target age groups for polio immunization campaigns

SIAs involving expanded age groups reduce overall caseloads, decrease transmission, and generally lead to a small reduction in the time to achieve WPV elimination. Analysis of preventive expanded age group SIAs in Tajikistan or prior to type-specific surges in incidence in high-risk areas of India and Nigeria showed the greatest potential benefits of expanded age groups. Analysis of expanded age group SIAs in outbreak situations or to accelerate the interruption of endemic transmission showed relatively less benefit, largely due to the circulation of WPV reaching individuals sooner or more effectively than the SIAs. The India and Nigeria results depend strongly on how well SIAs involving expanded age groups reach relatively isolated subpopulations that sustain clusters of susceptible children, which we assume play a key role in persistent endemic WPV transmission in these areas.

 To unsubscribe please send an email to cmorry@comminit.com with ‘unsubscribe quick links’ in the subject.  To subscribe do the same with ‘subscribe quick links’ in the subject.

SOMETHING NEW: If you want to go back to a previous Quick Links and can’t find it on your email they are now posted on the Polio Network website and can be found listed at this link. 

Cheers

Chris

For more information see:

CI Polio Network

GPEI Resources

UNICEFs Rhizome C4D site

A note on Quick Links: 

Quick Links is a small experiment from The Communication Initiative that might help those working for polio eradication in Pakistan and Afghanistan identify useful knowledge on issues the programme is facing.  It is designed to be brief and not add too much to anyone's inbox.  Each email focuses on an area of particular importance to the Pakistan and Afghanistan programmes and presents brief descriptions of three resources that may be of interest or use to those of you working in the country.  The mailing list, by design, is quite small though anyone who's interested can send a request to cmorry@comminit.comand they'll be added to the list.  We also welcome suggestions and requests for specific topics to be covered and/or resources to be identified.