Piloting delivery of PfSPZ vaccines for malaria through a cryogenic vaccine cold chain to travel and military medicine clinics.

BACKGROUND: PfSPZ vaccines comprising Plasmodium falciparum (Pf) sporozoites (SPZ) have demonstrated > 90% protection against variant Pf malaria infections for at least 12 weeks; they are the only vaccines with the level of efficacy necessary to protect travellers. PfSPZ are eukaryotic cells stabilized by cryopreservation and distributed using a cryogenic (below -150 °C) cold chain. The Ebola vaccine and mRNA vaccines against SARS-CoV-2 pioneered uptake of vaccines requiring non-standard ultra-low temperature cold chains. The cryogenic cold chain using liquid nitrogen (LN2) vapour phase (LNVP) cryoshippers, is simpler, more efficient than -80, -20 or 2-8 °C cold chains, and does not use electricity. This study was conducted to evaluate implementation and integration of a cryogenically distributed vaccine at travel and military immunization clinics. METHODS: We conducted sequential 28-day studies evaluating vaccine shipping, storage, maintenance and accession at two US military and two civilian travel health/immunization clinics. In each clinic, personnel were trained in equipment use, procurement and handling of LN2, temperature monitoring and inventory record keeping by in-person or video instruction. RESULTS: Sites required 2-4 h/person for two persons to assimilate and develop the expertise to manage vaccine storage and LNVP operations. LN2 for recharging cryoshippers was delivered every 1-2 weeks. Vaccine ordering, receipt, storage and inventory control was conducted effectively. Simulated single dose vaccine cryovial retrieval and thawing were performed successfully in different travel clinic settings. Continuous temperature monitoring at each site was maintained with only one short excursion above -150 °C (-145 °C) through shipping, use and reverse logistics. Staff, during and at study conclusion, provided feedback that has been incorporated into our models for cold chain logistics. CONCLUSIONS: These studies demonstrated that the training in delivery, storage, administration and integration of PfSPZ vaccines can be successfully managed in different immunization clinic settings for travellers and military personnel.

Zika Virus in an American Recreational Traveler.

We report the case of a 48-year-old American traveler who presented to our clinic with diffuse rash, malaise, fatigue, fever, arthralgia, low back pain, and bilateral exudative conjunctivitis. The patient had an extensive vaccination and travel history: most notable for prior receipt of yellow fever vaccine; extensive travel or residence in areas endemic for dengue, chikungunya, and West Nile virus; and recent travel to French Polynesia. Clinical and laboratory findings were consistent with Zika virus (ZIKV) infection. Our report highlights the need to include ZIKV in the differential diagnosis, especially in febrile patients with a rash returning from endemic areas.

Safety of Typhim Vi vaccine in a postmarketing observational study.

BACKGROUND: Typhoid fever is endemic in many parts of the world. In the United States, nearly three quarters of all cases are contracted by persons who traveled to regions with endemic disease. Typhim Vi, a vaccine containing the purified cell surface Vi polysaccharide of the Salmonella enterica serovar Typhi, was developed to provide protection against typhoid fever. We present the results of the largest safety study of this Vi vaccine to date. METHODS: This open-label, descriptive study assessed safety and reactogenicity following the Vi vaccine administration. Coadministration of other vaccines (at separate sites) was permitted, consistent with clinical practice. Participants aged 2 years or older with no known sensitivities to any vaccine component, who received the Vi vaccine, according to label directions, at a participating travel clinic, were eligible to participate. Information was collected on concurrent medications and medical conditions. The occurrence of solicited injection site reactions and systemic reactions was recorded on diary cards for 7 days following vaccination, along with any unsolicited medical events. Serious adverse events were reported for 30 days postimmunization. RESULTS: A total of 1,204 participants (mean age: 37.2 y, range: 2-82 y, 55% female) were enrolled into the study, and 1,111 completed the 7-day follow-up. The most common solicited reactions were injection site pain [850 of 1,111 (76.5%)], tenderness [838 of 1,111 (75.4%)], and muscle aches [434 of 1,111 (39.1%)]. Fever was reported in 18 (1.6%) of 1,111 participants. Coadministration of other common travel vaccines did not affect reactogenicity profiles, except for an increase in the Vi vaccine injection site redness when two vaccines were administered in the same limb. CONCLUSIONS: The Vi vaccine was well tolerated in an unselected population, aged 2 to 82 years, presenting to a travel clinic for vaccination.