Vaccine News

Health officials recently confirmed the third positive case of chikungunya in Costa Rica for 2026, based on laboratory results from the Caja Costarricense de Seguro Social.

The Costa Rican Ministry of Health reported in April 2026 that a 45-year-old foreign national living in Guanacaste province entered the country during the virus's incubation period.

This new case follows two earlier cases reported in January 2026 in the Esparza canton of Puntarenas province. In contrast, Costa Rica recorded only 7 chikungunya cases in 2025.

The Central American country has seen significant declines in other vector-borne illnesses in 2025 due to intensified control efforts:

- Dengue: Approximately 3,983 cases reported through mid-September, representing an 82.5% decrease compared to the same period in 2024.

- Malaria: A total of 53 cases were reported for the entire year, with only 8 locally transmitted cases, marking a reduction of over 94% from 2024.

- Zika: Around 11 cases reported by July, down from 32 in 2024.

Additionally, cases of New World screwworm myiasis have been reported in countries where it had previously been eliminated, including Costa Rica.

The Ministry of Health is urging residents and visitors to eliminate standing water, use repellents, and take personal protection measures to prevent local transmission of these viruses.

As of April 13, 2026, the U.S. CDC has not issued a Travel Health Notice for Costa Rica, but it does offer travel vaccination advice. 

As warmer weather and spring rains signal the start of another mosquito season in Florida, health officials are urging both residents and visitors to take extra precautions against diseases such as Dengue, chikungunya, and malaria.

While local transmission of these viruses remains relatively low in 2026 compared with previous years, 2025 saw several locally acquired infections, particularly in Southeast Florida.

Early data from from Miami-Dade County suggest that continued vigilance is essential in 2026.

The latest arbovirus surveillance report from the Florida Department of Health (#13), as of April 4, 2026, indicates ongoing activity, with 20 travel-associated cases of Dengue, 28 travel-associated cases of chikungunya fever, and 10 reported malaria cases—all in individuals who recently traveled to areas where malaria is endemic.

"Florida's subtropical climate and densely populated areas make us particularly vulnerable," said a spokesperson for the Florida Department of Health in recent surveillance updates. "While we have robust mosquito control programs in place, individual actions remain critical.”

"Residents who experience fever, joint pain, rash, or severe headaches after being bitten by mosquitoes are advised to seek medical attention promptly and inform healthcare providers of any recent travel or local exposure. Testing and reporting are vital for helping officials track and respond to potential outbreaks."

Unlike many infectious diseases, most mosquito-borne illnesses in Florida do not have widely available vaccines for the general public.

However, for chikungunya, the U.S> FDA-approved VIMKUNYA vaccine is available throughout the United States. It can be accessed at Florida travel clinics and select pharmacies, but it is not routinely recommended for everyday residents.

Currently, Dengue and malaria vaccines are available in other countries; they are not available in the USA as of April 12, 2026.

Dengue fever transmission continues to affect New Caledonia, with health authorities reporting over 640 cases (both probable and confirmed) since the start of 2026.

Weekly case counts have steadily increased since February 2026, with notably high notifications during epidemiological weeks 11 to 13, indicating sustained community transmission within this French overseas territory.

The epidemic phase, which was declared in late March, remains active.

Virus transmission is predominantly occurring outside the Greater Nouméa area, where the spread has been more rapid. In contrast, case numbers within Greater Nouméa—including Dumbéa, Mont-Dore, Nouméa, and Païta—remain relatively lower and more stable. 

Local officials attribute this protective effect to the successful release of Wolbachia-infected mosquitoes through the World Mosquito Program, which has significantly reduced the ability of Aedes aegypti mosquitoes to transmit the virus in treated urban zones. 

Health authorities have issued a red alert for DENV-1, urging heightened vigilance and preventive measures across the territory. New Caledonia is not currently implementing a Dengue vaccination campaign as part of its public health response.

Although the Dengue vaccine Qdenga® is authorized in the European Union (including France) and available in many countries, it is not routinely available or offered through the Directorate of Health and Social Affairs in New Caledonia. 

Health authorities emphasize that preventing mosquito bites remains the most effective and immediate defense during this epidemic. In 2025, approximately 60,000 travelers visited New Caledonia, which is located off the east coast of Brisbane, Australia.

As of April 11, 2026, the U.S. CDC's Level 1 Practice: Usual Precautions, Global Dengue Notice advises travelers in risk areas to take precautions to avoid mosquito bites, since Dengue vaccines are unavailable in the USA.

With South Carolina's measles outbreak now under control and no new cases reported recently, Utah has become the state with the highest active transmission of the disease in the country.

As of April 10, 2026, state health officials have confirmed 24 new cases in the past five days, bringing Utah's total outbreak count to 583.

Of these, 386 cases have been recorded this year, including 121 in the last three weeks alone. So far, 47 people have been hospitalized due to the outbreak.

The Southwest Health Area accounts for the largest share of cases, with 249 reported.

In the urban areas, Utah County follows with 93 cases, and Salt Lake County has reported 62 cases.

Local health authorities are reminding residents that measles is extremely contagious and can lead to serious complications, particularly among young children, pregnant individuals, and those with weakened immune systems.

While most of these measles cases have been reported in unvaccinated people, MMR vaccination coverage among Utah kindergartners was about 88% during the 2024–2025 school year.

Utah continues to urge families to ensure that they are up to date on the MMR vaccine, which remains the most effective way to prevent the spread of this disease.

With Lyme disease season soon to spike in the Northeast, two pharmaceutical companies recently announced very positive news about a vaccine candidate.

Pfizer Inc. and Valneva SE announced on March 23, 2026, topline results from the Phase 3 VALOR "Vaccine Against Lyme for Outdoor Recreationists" clinical trial (NCT05477524) of its investigational 6-valent OspA-based Lyme disease vaccine candidate PF-07307405 (LB6V, formerly known as VLA15).

In the pre-specified analyses: Efficacy of 73.2% from 28 days post-dose 4 (season 2) in reducing the rate of confirmed Lyme disease cases compared to the placebo arm (95% CI 15.8, 93.5); Efficacy of 74.8% from 1-day post-dose 4 (season 2) in reducing the rate of confirmed Lyme disease cases compared to the placebo arm (95% CI 21.7, 93.9)

The press release stated, 'Given the clinically meaningful efficacy and the fact that the 95% confidence interval lower bound was above 20 in the second pre-specified analysis, Pfizer is confident in the vaccine's potential and is planning submissions to regulatory authorities.'

"Lyme disease can cause potentially serious consequences – where individuals and families face symptoms that can disrupt daily life, work, and long-term health – and there is currently no vaccine available," said Annaliesa Anderson, Ph.D., Senior Vice President and Chief Vaccines Officer, Pfizer. "The efficacy shown in the VALOR study of more than 70% is highly encouraging and creates confidence in the vaccine's potential to protect against this disease that can be debilitating."

As of late March 2026, the U.S. CDC reports that the bacteria that cause Lyme disease are transmitted to humans by blacklegged (Ixodes) ticks. Infected ticks must be attached for over 24 hours to transmit the infection, so that prompt removal can prevent transmission. These ticks are most commonly found in forested areas of the northeastern, north-central, and mid-Atlantic states, as well as parts of the Pacific Coast.

The CDC reports that recent estimates using other methods suggest that approximately 476,000 people may be diagnosed and treated for Lyme disease each year in the United States. This number likely includes patients who are treated based on clinical suspicion but do not actually have Lyme disease.

Since September 2022, over 1,000 confirmed and possible cases of shigellosis and other gastrointestinal infections have been reported among travelers returning from the Republic of Cabo Verde to Europe, the United Kingdom, and the United States. 

New cases continue to emerge in late March 2026, more than three years into the outbreak.

This information comes from the latest update by the European Centre for Disease Prevention and Control (ECDC). In an epidemiological alert published on March 18, 2026, the ECDC reported a total of 766 confirmed and suspected cases of shigellosis across 13 EU/EEA countries, the UK, and the US.

Additionally, around 300 cases of other gastrointestinal infections — including salmonellosis, cryptosporidiosis, giardiasis, campylobacteriosis, and pathogenic Escherichia coli — have also been identified.

Despite ongoing investigations by local, European, and international health authorities, the exact source of these infections, which are believed to be food- or waterborne, has not yet been identified. Most of the affected travelers had stayed at the same hotel chain in the Santa Maria region on the island of Sal, a popular all-inclusive resort destination.

Cabo Verde is an archipelago of islands and islets located in the Atlantic Ocean, about 385 miles off the coast of West Africa.

As of March 24, 2026, the United Kingdom has reported 263 cases, while the United States has reported 7 cases.

The ECDC assesses the likelihood of new infections among travelers visiting the Santa Maria region of Sal as moderate, as the source remains uncontrolled. The dominant strain identified is Shigella sonnei, which causes severe diarrhea (often bloody), fever, abdominal cramps, and dehydration. Some strains exhibit antibiotic resistance, complicating treatment.

Further cases are anticipated until effective control measures are put in place.

Travelers returning from Sal who experience persistent diarrhea, bloody stools, fever, or severe stomach cramps should seek medical attention immediately and inform their healthcare provider about their recent travel history.

Currently, no licensed vaccine is available for shigellosis or the other pathogens involved in this outbreak. However, promising candidates such as Valneva and LimmaTech's tetravalent Shigella4V2 (S4V2) bioconjugate vaccine candidate are advancing through Phase 2 clinical trials.

Campania health authorities in Italy have confirmed a significant increase in hepatitis A cases, with 133 confirmed infections reported since January 2026.

As of March 20, 2026, the outbreak, which is centered around Naples and Capri, is primarily linked to the consumption of raw or undercooked bivalve mollusks, such as mussels, clams, and oysters that have been contaminated with the hepatitis A virus.

Additionally, there is evidence suggesting possible secondary person-to-person transmission contributing to this year's outbreak.

Currently, more than 40 to 50 patients are hospitalized at Naples' Cotugno Hospital.

In response to the outbreak, local media reported Naples Mayor Gaetano Manfredi issued an emergency ordinance on March 19-20, banning the sale and consumption of raw seafood in public establishments.

Residents and tourists are urged to thoroughly cook shellfish, practice strict hand hygiene, and avoid raw seafood. Campania, located on Italy's southern coast, is a major tourism hub, attracting approximately 20 million tourists annually.

This situation highlights the recurring food safety challenges faced by international travelers in 2026.

Public health officials recommend vaccination for at-risk groups and emphasize the need for continued vigilance to prevent further spread of the virus.

When departing from the USA for international travel in 2026, hepatitis A vaccination services are offered at travel vaccine clinics.