Editorial

The re-emergence of measles in developed countries: Time to develop the next-generation measles vaccines?

The current health emergency caused by COVID-19 disease shows several correspondences with well-known epidemics of the past. The knowledge of their management and overcoming could give us useful tools to face the present COVID-19 pandemic and future epidemics.

On 1 March 1801, the first smallpox vaccinations were carried out in Palermo, and a few weeks later, the vaccine was also administered in Naples and the various provinces of the Kingdom. We aim to study the mass vaccination programme initiated by the Bourbon king Ferdinand IV that was the first large-scale campaign to be conducted in Italy and one of the first in Europe.

The authors searched and examined historical testimony and different aspects linked to the public health issues on vaccination. It is a topical topic in the current period with the COVID pandemic.

Albeit with the due differences determined by the passage of time and by the scientific and cultural advances of modern society, this testimony from the past can provide us with food for thought regarding how to face the present COVID-19 pandemic and to prepare for the future. Indeed, it shows us how the terrible smallpox epidemic was handled and finally overcome, thanks to vaccination.

Vaccination has saved millions of lives. Vaccine hesitancy was recently declared a major threat to health by the World Health Organisation. Sociodemographic variables and knowledge level about vaccines have been suggested previously to affect vaccine uptake.

This study aimed to investigate how levels of vaccination knowledge and concerns around safety of vaccines varied across sociodemographic factors in the European Union and United Kingdom. Levels and sources of knowledge and vaccine attitude patterns were examined across different areas of Europe.

Data from the March 2019 Eurobarometer survey was used in this study which had 27,524 participants across the European Union and the United Kingdom. Two-level logistic and linear regressions were used to look for associations between sociodemographic variables, vaccine attitudes and knowledge level.

Those who trusted information from healthcare workers and healthcare authorities were most likely to have positive vaccine attitudes; those trusting internet sources the most were the least likely. Those with greater vaccine related knowledge were more likely to report positive vaccination attitudes.

Healthcare workers are key to dissemination of vaccination advice however many are becoming hesitant themselves. An increasing number of people are seeking online sources for vaccination information, and this has implications with information accuracy and vaccine hesitancy. A considerable proportion of the adult population in the European Union and the United Kingdom was concerned about the safety or side effects of vaccines. Continued efforts to increase trust in vaccines both in whole populations and specific groups are needed.

In addition to host genetic and environmental factors, variations in immune responses to vaccination are influenced by demographic variables, such as race and sex. The influence of genetic race and sex on measles vaccine responses is not well understood, yet important for the development of much-needed improved measles vaccines with lower failure rates. We assessed associations between genetically defined race and sex with measles humoral and cellular immunity after measles vaccination in three independent and geographically distinct cohorts totaling 2872 healthy racially diverse children, older adolescents, and young adults. We found no associations between biological sex and either humoral or cellular immunity to measles vaccine, and no correlation between humoral and cellular immunity in these study subjects. Genetically defined race was, however, significantly associated with both measles vaccine-induced humoral and cellular immune responses, with subjects genetically classified as having African-American ancestry demonstrating significantly higher antibody and cell-mediated immune responses relative to subjects of Caucasian ancestry. This information may be useful in designing novel measles vaccines that are optimally effective across human genetic backgrounds.

Despite the existence of an effective measles vaccine, resurgence in measles cases in the USA and across Europe has occurred, including in individuals vaccinated with two doses of the vaccine. Host genetic factors result in inter-individual variation in measles vaccine-induced antibodies, and play a role in vaccine failure. Studies have identified HLA (human leukocyte antigen) and non-HLA genetic influences that individually or jointly contribute to the observed variability in the humoral response to vaccination among healthy individuals. In this exciting era, new high-dimensional approaches and techniques including vaccinomics, systems biology, GWAS, epitope prediction and sophisticated bioinformatics/statistical algorithms provide powerful tools to investigate immune response mechanisms to the measles vaccine. These might predict, on an individual basis, outcomes of acquired immunity post measles vaccination.

This study examined the impact of rubella immunization, implemented in Hong Kong in phases since 1978, on antenatal rubella serological status in Chinese women.

In a retrospective cohort study, the incidence of antenatal rubella seronegative status in our parturients managed from 1998 to 2013 was analyzed by their year-of-birth as follows: <1965 (no childhood immunization), 1965–1982 (single dose at Primary 6), and ≥1983 (two doses at age 12 months and 12 years), adjusting for other factors including age, parity, body mass index, place-of-birth status and hepatitis B surface antigen (HBsAg) status.

Rubella seronegativity decreased from 12.9%, 10.5%, to 9.8% respectively, and correlated inversely (P < 0.001) with year-of-birth cohorts. Despite similar demographic profiles, this correlation was found only in Hong-Kong-born women (from 12.6%, 7.5% to 6.5% respectively), who also had significant lower incidences of rubella seronegativity (OR 0.73, 0.31 and 0.29 respectively) and HBsAg seropositivity (OR 1.09, 0.63 and 0.48 respectively) than China-born women. On regression analysis, rubella seronegativity was actually significantly increased following the implementation of immunization (aOR 1.20) while it was the reverse for non-residents (aOR 0.61).

Although rubella seronegativity decreased with immunization, the effect was less than expected when adjusted for other risk factors.