Identifying UK travellers at increased risk of developing pneumococcal infection: a novel algorithm

Abstract

Background: In 2016, the travel subcommittee of the UK Joint Committee on Vaccination and Immunisation (JCVI) recommended that 13-valent PCV (PCV13) could be offered to travellers aged over 65 years, visiting countries without infant PCV immunization programmes. This study aimed to identify, collate and review the available evidence to identify specific countries where UK travellers might be at an increased risk of developing pneumococcal infection. The data were then used to develop an algorithm, which could be used to facilitate implementation of the JCVI recommendation.

Methods: We conducted a systematic search of the published data available for pneumococcal disease, PCV vaccine implementation, coverage data and programme duration by country. The primary data sources used were World Health Organization databases and the International Vaccine Access Centre Vaccine Information and Epidemiology Window-hub database. Based on the algorithm, the countries were classified into 'high overall risk', 'intermediate overall risk' and 'low overall risk' from an adult traveller perspective. This could determine whether PCV13 should be recommended for UK adult travellers.

Results: A data search for a total of 228 countries was performed, with risk scores calculated for 188 countries. Overall, 45 countries were classified as 'high overall risk', 86 countries as 'intermediate overall risk', 57 countries as 'low overall risk' and 40 countries as 'unknown'.

Conclusion: To our knowledge this is the first attempt to categorize the risk to UK adult travellers of contracting pneumococcal infection in each country, globally. These findings could be used by national travel advisory bodies and providers of travel vaccines to identify travellers at increased risk of pneumococcal infection, who could be offered PCV immunization.

Keywords: Travel; pneumococcal disease; prevention; risk algorithm; traveller; vaccination.

Figure 1

PCV travel algorithm. At-risk population: as defined in Chapter 25 of the Green Book. Country of travel: combines country-specific data to categorize potential risk of contracting pneumococcal infection per country. Length of stay ± other factors: to consider travel for more than 3–4 weeks, gathering in dense crowds, working with local communities, Hajj Pilgrimage, or travelling during ‘flu’ season

Figure 2

Level of pneumococcal disease (invasive and non-invasive)—cases per 100 000 population. igh level of disease (≥250 cases/100 000) shown in RED; intermediate level of disease (51–249 cases/100 000) shown in AMBER; low level of disease (≤50 cases/100 000) shown in GREEN; unknown level of disease shown in GREY

Figure 3

Pneumococcal conjugate vaccines (PCV) immunization coverage among 1 year olds (%). Low coverage (≤50%) shown in RED; intermediate coverage (51–79%) shown in AMBER; high coverage (≥80%) shown in GREEN; countries with no childhood vaccination programmes shown in BLACK; unknown coverage shown in GREY

Figure 4

Time since PCV childhood vaccination programme was introduced (number of years). Short programme duration (≤2 years) shown in RED; intermediate programme duration (>2–<5 years) shown in AMBER; long programme duration (≥5 years) shown in GREEN; countries with no childhood vaccination programmes shown in BLACK; unknown programme duration shown in GREY

Figure 5

Data synthesis for the PCV travel vaccine algorithm; combining country-specific data to categorize potential risk of contracting pneumococcal infection. High overall risk (score ≥ 8 points or two RED parameters) shown in RED; intermediate overall risk (score 4–7 points) shown in AMBER; low overall risk shown in GREEN (score 2–3 points); unknown overall risk shown in GREY. Countries using PCV13 in childhood vaccination programmes visualized with vertical lines; countries using PCV10 in childhood vaccination programmes visualized with horizontal lines; and countries using both PCV13 and PCV10 in childhood vaccination programmes visualized with cross-hatched lines