Vaccine News

Most older adults and immunocompromised individuals are familiar with herpes zoster (HZ), which causes painful rashes upon activating the varicella-zoster virus (VZV).

Although the U.S. FDA has approved a vaccine (Shingrix®) for preventing shingles, its administration is commonly associated with high reactogenicity.

On March 14, 2025, results from a new study published by the journal Nature focused on ten different vaccine candidate designs using two different codon optimizations targeting the VZV glycoprotein E (gE).

For this evaluation, researchers developed several VZV modRNA vaccine candidates targeting the glycoprotein gE, one of the most abundant proteins on the surface of the virion.

A subset of mRNA constructs was formulated into lipid nanoparticles and assessed for their ability to induce specific cellular and humoral immune responses in mice following vaccination.

Notably, the selected mRNA vaccine candidates induced high antibody levels and robust CD4+ and CD8+ immune responses.

Moreover, this study showed that alternate lyophilized vaccines provide comparable immunogenicity to liquid frozen formulations and are stable under long-term storage conditions.

Some of these investigational VZV modRNA candidates, including a lyophilized presentation, are currently being tested in a Phase I/II clinical study sponsored by Pfizer Inc.

This study's primary completion estimate is in late 2025.

While somewhat similar, no herpes simplex virus (HSV) vaccines are approved for use in 2025. However, this is an HSV mRNA vaccine candidate conducting research as of March 2025.

Since the U.K. Health Security Agency (UKHSA) declared a national measles incident in parts of England in 2024, cases have been reported in various cities besides London.

So far in 2025, 151 measles cases have been confirmed in Yorkshire and Humber, in the South West, Bristol, Leeds, Hertfordshire, and in London.

As of March 13, 2025, no acute measles-related deaths have been reported in 2025.

Last year, the UKHSA reported the most measles cases (2,911) in England in over a decade.

To England's east, 127,350 people were diagnosed with measles in Europe in 2024, led by Romania (27,568). The WHO says this is the highest number of measles cases in over 25 years.

“Measles is back, and it’s a wake-up call.... without high vaccination rates, there is no health security,” warned Dr Hans Henri P. Kluge, WHO Regional Director for Europe, in a media statement.

“The measles virus never rests – and neither can we.”

While the U.S. Centers for Disease Control and Prevention (CDC) recent Travel Health Notice identifies 57 countries reporting measles cases, it does not mention England.

However, the CDC does suggest that anyone visiting a measles outbreak area be fully protected from this contagious virus with the MMR vaccine, which is generally available at clinics and pharmacies in the U.S.

As the world is confronted with an increasing number of countries reporting polio cases and poliovirus detections, an innovative vaccination strategy has been launched in polio hot spots.

According to the Global Polio Eradication Initiative, the Islamic Republic of Pakistan reported six WPV1 cases in March 2025. Last year, there were 74 polio cases, primarily in Balochistan, Punjab, Khyber Pakhtunkhwa, and Sindh.

To reduce this outbreak, polio vaccination campaigns are deploying innovative delivery solutions.

On March 13, 2025, PharmaJet® announced that their Tropis intradermal (ID) delivery system was used in Pakistan's latest World Health Organization (WHO) polio eradication campaign in February 2025.

Tropis is the first and only needle-free ID delivery technology to achieve WHO prequalification.

Tropis was used to deliver a fractional dose of inactivated polio vaccine (fIPV) in parallel to oral polio vaccine (OPV) administration as part of a WHO-recommended strategy to boost humoral immunity.

Previous data from poliovirus campaigns and routine immunizations in Pakistan, Somalia, and Nigeria have demonstrated that Tropis delivery can improve coverage, decrease cost, and increase acceptability. The data also showed that Tropis is an effective and preferred solution for polio immunization campaigns that can help increase campaign coverage by over 18%.

Also, another study found the potential for up to a 47% decrease in total immunization costs, and 95% of healthcare workers preferred Tropis compared with the SoC.

Paul LaBarre, Vice President of Global Business Development at PharmaJet, commented in a press release, "The Tropis needle-free system is very effective and affordable in campaigns and routine immunizations, protecting nearly 12 million children against poliovirus."

"There is still a lot of work to do, and we are committed to achieving eradication goals so that no child suffers from paralytic polio."

In early 2025, the U.S. CDC reissued a Travel Health Notice regarding polio outbreaks and poliovirus detections in 39 countries to alert travelers of the risks.

In the United States, IPVs have been used to protect people from polio since 2000; OPVs are unavailable in the country.

The CDC recommends that international travelers planning to visit a polio-endemic area speak with a travel vaccine expert about immunization options at least one month before departure abroad.

Since the start of the 2024/2025 dengue season in the Argentine Republic during week #31 of 2024, 1,443 cases have been confirmed by the Ministry of Health.

As of March 10, 2025, 96.9% of these dengue cases had no travel history, indicating substantial local mosquito transmission.

Argentina's Central (816) and Northwest (237) regions have reported the most cases this season.

There have been 45 cases with a travel history corresponding to people who traveled to Brazil, Cuba, Mexico, the Maldives, Thailand, India, Peru, Paraguay, and Colombia.

Likewise, millions of international travelers arrived in Argentina last year, most visiting Buenos Aires.

In 2024, about 581,000 dengue cases and 400 related fatalities were reported in Argentina. 

As part of the Strategic Plan for Dengue Prevention and Control 2024-2025, Argentina's Minister of Health, Mario Lugones, chaired a meeting on March 11, 2025, regarding actions being carried out, the results achieved to date, and the lines of work to be followed to support and strengthen the jurisdictions' response capacity to address future dengue outbreaks,

Progress was also shared on developing a new national dynamic map that will include geographic, demographic, and climatic data linked to rainfall and temperature records across the country. This will allow for the adoption of preventive measures and the anticipation of potential dengue outbreaks.

To alert international visitors of the health risk, the U.S. CDC reissued a Travel Helath Advisory for the dengue epidemic in the Americas. Since dengue vaccines are currently unavailable in the U.S., the CDC recommends avoiding mosquito bites for travelers to endemic areas.

Additionally, Argentina's Zika virus outbreak has accelerated in 2025, now recording 288 cases this year.

The CDC does recommend various routine and travel vaccinations, such as for chikungunya and yellow fever, before visiting Argentina in 2025.

With over 13,000 Americans visiting Samoa in 2024 and more people arriving in 2025, the U.S. Department of State evaluated its travel advisory for the Independent State of Samoa.

On March 10, 2025, the State Department reissued a Level 1: Exercise Normal Precautions, Travel Advisory for Samoa, an island country in Polynesia. There is a country-wide population of about 200,000 in Savai'i and Upolu and on the smaller islands of Manono and Apolima.

Often confused with American Samoa, an unincorporated territory of the U.S., Samoa, previously known as Western Samoa, is about 100 miles away.

According to the local tourist board, the impact of Map Samoa has been profound. It has simplified travel planning, making it easier for tourists and visitors to discover and explore Samoa’s hidden gems.

Suppose you decide to visit this Pacific Ocean paradise in 2025. In that case, the local U.S. embassy suggests enrolling in the Smart Traveler Enrollment Program to receive digital alerts and to ensure you can be located in an emergency.

From a health perspective, the U.S. CDC has not included Samoa in its recent travel advisories.

However, the CDC recommends that future visitors to Samoa speak with a vaccination expert about route and travel vaccine options for diseases such as measles, typhoid, and yellow fever.

International travelers visiting countries in Africa in 2025 should be aware of the health risks associated with the ongoing cholera outbreak.

Cholera is a potentially fatal infection that causes severe diarrhea but can be prevented with vaccination.

While cholera is no longer a health risk in the United Kingdom (UK), it is sometimes reported in returning travellers from three WHO regions.

For example, the UK's Travel Health Pro reported on March 7, 2025, that four cases of cholera (toxigenic Vibrio cholerae serogroup O1) were locally diagnosed in mid-February 2025.

Three UK travellers were recently diagnosed with cholera after visiting the Federal Democratic Republic of Ethiopia.

A fourth UK cholera case did not travel but reported consuming water from Ethiopia by one of the returned travellers before experiencing symptoms.

Ethiopia is just one of 22 areas the WHO currently identifies as a risk for cholera.

A cholera vaccine can be considered for travellers departing from the UK following a full risk assessment and those with limited access to safe water and/or underlying health problems.

According to the U.S. CDC, cholera remains a global health risk.

And when leaving the United States in March 2025, the U.S. CDC recommends that travelers speak with a travel vaccine expert about cholera prevention options. Following increased production, cholera vaccines have become more available this year.

Brazil's Ministry of Health (MOH) has been reporting data on the locations of Chikungunya patients for the past three years.

As of March 11, 2025, the MOH reported that most of the 40,000 Chikungunya cases reported this year were found in Sao Paulo (5,714) and Minus Gerias (5,120).

Last year, there were about 265,000 Chikungunya cases and 231 related fatalities in Brazil, located in similar states.

The Chikungunya virus is transmitted to people through the bite of an infected mosquito of the Aedes spp., which are found at beaches and in mountains below seven thousand feet in elevation. 

While the U.S. CDC has not issued a Travel Health Advisory regarding Brazil's ongoing Chikungunya outbreak, it writes, 'There has been evidence of chikungunya virus transmission in Brazil within the last five years.'

Chikungunya vaccination may be considered for seniors, especially those with underlying medical conditions, who may spend at least two weeks (cumulative time) in indoor or outdoor areas where mosquitoes are present in Brazil, or visitors planning to stay in Brazil for a cumulative period of six months or more.

Before departing for Brazil, most travel clinics and pharmacies in the United States offer the U.S. FDA-approved chikungunya vaccine. Valneva SE's IXCHIQ® vaccine has been found safe and effective in various studies.