Vaccine News

Health authorities in French Guiana, an overseas department of France located on the northeast coast of South America, have confirmed the re-emergence of local Chikungunya transmission for the first time since 2015.

The initial case was identified in a resident of Kourou by the French Guiana Regional Health Agency through RT-PCR testing on January 27, 2026.

This case was classified as locally acquired, meaning the patient contracted the virus from a mosquito bite in French Guiana, without having recently traveled to affected areas like Brazil. Subsequent investigations have revealed three additional confirmed cases.

The virus strain detected in these cases is genetically similar to the one currently circulating across parts of the Americas, according to the Pan American Health Organization (PAHO), which issued an epidemiological alert on February 10, 2026.

The alert noted the resumption of transmission in the Guiana Shield region—including Guyana, French Guiana, and Suriname.

The PAHO has urged heightened preparedness across the Americas amid rising chikungunya activity in several countries since late 2025. The reappearance of local transmission in areas long free of the Chikungunya virus underscores the risk posed by ongoing viral activity in neighboring countries and the potential for imported cases to spark outbreaks

This resurgence aligns with broader regional trends in 2025.

PAHO data indicate sustained increases in chikungunya cases in parts of South America and the Caribbean since late 2025, even as overall regional numbers have declined compared to the peaks in 2024.

The situation is under close monitoring by French health authorities and international partners, with no reports of severe complications or large-scale outbreaks at this stage.

However, in central South America, the U.S. Centers for Disease Control and Prevention (CDC) has identified parts of Bolivia as experiencing an ongoing chikungunya outbreak.

Currently, the CDC says there is no specific antiviral treatment; management focuses on symptom relief, and prevention relies on mosquito control and personal protective measures such as repellents, long clothing, and eliminating breeding sites.

Travelers to the region are encouraged by the PAHO and other agencies to consult health guidelines and consider protective measures, such as vaccination, before visiting the Guiana Shield region as of February 16, 2026.

The U.S. Centers for Disease Control and Prevention (CDC) has identified parts of Bolivia as health risk destinations in South America due to an ongoing outbreak of chikungunya fever, a mosquito-borne viral illness.

As of mid-February 2026, there have been 1,534 confirmed or suspected cases reported nationwide.

A Travel Health Notice issued on February 11, 2026, classifies the situation as a Level 2 – Practice Enhanced Precautions, specifically highlighting outbreaks in the departments of Santa Cruz (eastern Bolivia) and Cochabamba (central Bolivia), while smaller numbers have been noted in Tarija (14), Beni (10), and Chuquisaca (7).

The CDC writes that Chikungunya, primarily transmitted by Aedes aegypti and Aedes albopictus mosquitoes, causes symptoms such as high fever, severe joint pain, muscle pain, headache, nausea, fatigue, and rash. While most individuals recover within a week, some may experience persistent joint pain for months or even years. Severe complications are rare but can occur, especially in vulnerable groups such as older adults, infants, and those with underlying health conditions.

There is no specific antiviral treatment available, but the CDC recommends a vaccine for travelers visiting outbreak areas. 

In its notice, the CDC urges travelers to Bolivia, especially those visiting affected regions, to take proactive measures to avoid mosquito bites.

The outbreak in Bolivia is part of a broader regional trend in the Americas.

The Pan American Health Organization (PAHO) noted sustained increases in chikungunya cases since late 2025, with a re-emergence in areas such as the Guiana Shield (Guyana, French Guiana, Suriname) after nearly a decade without reports.

In 2025, the Americas reported 313,132 cases (113,926 confirmed, including 170 deaths) across 18 countries and one territory, though overall regional numbers declined compared to 2024.

The CDC and PAHO say travelers to outbreak areas should consult travel health providers about vaccination options before their trips and monitor updates, as conditions can evolve rapidly due to changes in mosquito populations and environmental factors.

The U.S. Centers for Disease Control and Prevention (CDC) has released its latest Weekly U.S. Influenza Surveillance Report for Week 5, confirming the 2025-2026 flu season activity remains elevated nationally.

However, patterns are shifting as the season progresses.

According to the CDC on February 13, 2026, influenza A activity is decreasing nationally and in most regions, while influenza B activity is increasing in many areas. Regional trends vary; some parts of the country are experiencing stable or declining levels, while others continue to see ongoing circulation of the virus.

A significant concern raised in the report is the addition of six influenza-associated pediatric deaths recorded last week.

Four of the deaths were linked to influenza A viruses, with two cases identified as A(H3N2). The remaining two deaths were associated with influenza B viruses, although no lineage was determined.

This unfortunate news brings the cumulative total for the 2025-2026 season to 66 reported influenza-associated pediatric deaths.

Currently, precise state-by-state pediatric death locations or counts are not publicly disclosed by the CDC.

These totals compare with the last three full seasons: 2022-2023 season: 187 pediatric deaths reported; 2023-2024 season: 210 pediatric deaths reported; 2024-2025 season: 289 pediatric deaths reported, the highest for any non-pandemic season.

Among children eligible for vaccination who had known vaccination status, the CDC's data indicates that approximately 90% of these deaths occurred in those who were not fully vaccinated against influenza.

With about 130 flu shots already distributed in the U.S., access to vaccines such as FluMist continues in February 2026.

For the full CDC report and detailed surveillance data, visit the CDC's FluView website. Please note that all figures are preliminary and subject to updates as more reports are received.

For more than 100 years, the effectiveness of tuberculosis (TB) vaccines has varied based on the type of vaccine used.

As of 2026, there are over ten TB vaccines in circulation, prompting researchers to explore ways to enhance their effectiveness in decreasing the number of new cases.

Given the rising number of TB cases in the United States and other countries in 2026, this research is crucial for reducing the incidence of the disease.

According to a mathematical modeling study, the population-level success of new TB vaccines could hinge on their ability to block infectious asymptomatic TB, where people transmit the bacteria without symptoms.

Using models based on high-burden settings, researchers compared three vaccine scenarios: preventing progression to infectious symptomatic TB only; preventing progression to any infectious disease, including asymptomatic disease; and preventing progression to any disease.

Across all short-term (3-year) scenarios, symptomatic TB cases were reduced by a similar amount (≈1.6–2.3%).

Over longer periods (20 years), vaccines that block infectious asymptomatic disease averted far more cases—19.4% and 23.3% vs. just 7.3% in the symptomatic-only scenario—mainly by curbing silent transmission.

Published in PLOS Medicine on February 12, 2026, the study highlights that overlooking efficacy against asymptomatic infection could underestimate the long-term benefits of new TB vaccines in ending the global epidemic.

These researchers also evaluated scenarios in which they hypothetically assumed the vaccines would be effective in the pre-symptomatic stages at the time of vaccination.

If this were the case, they would have seen greater impact from the vaccines because they protected a larger proportion of the population, specifically those at high risk of progressing to later stages of disease.

However, experts believe that it is unlikely that a vaccine would be effective if delivered to someone with the disease at the time of vaccination, as the immune response would overwhelm any vaccine effect.

Although it is not yet known whether the same applies to earlier disease stages (such as nTB) and to undulation between disease stages, these researchers wrote.

With international travel forecast to increase again in 2026, a group of innovative vaccines is showing positive trends.

Bavarian Nordic A/S today announced its preliminary, unaudited financial results for 2025, highlighting strong demand for its travel vaccines.

On February 12, 2026, the company confirmed that its Travel Health business exceeded its latest financial guidance, reporting a 30% increase compared to 2024.

The demand for its existing rabies and Tick-Borne Encephalitis vaccines continued to grow, with increases of 34% and 20%, respectively.

Additionally, the first-year sales of the chikungunya vaccine (VIMKUNYA®) reached DKK 85 million (approximately $13.4 million).

While the mosquito-transmitted chikungunya virus has affected over 100 countries since its emergence, the state of Florida is reporting numerious travel-related cases and even an unusual local case in early 2026.

These increases exceed the global international travel activity, which only increased by 4% from 2024 to 2025, according to data from UN Tourism.

Paul Chaplin, President and CEO of Bavarian Nordic, commented in a press release, "We are encouraged by these extraordinary results."

We remain, however, the leading provider to governments of mpox and smallpox vaccines to support their public health responses, whether during outbreaks or for long-term stockpiling, and we continue to build strong partnerships to expand the base business."

The unedited company press release is found at this link.

Hong Kong's Centre for Health Protection (CHP) reported two new human cases of H9N2 avian influenza infection from mainland China, with symptom onset in late December 2025 and mid-January 2026.

The announcement, published on February 10, 2026 (Week 6), highlighted ongoing sporadic detections of the low-pathogenic bird flu virus in humans.

These cases in Hubei, Guangxi, and Jiangsu provinces coincided with the reporting of an additional human infection involving avian influenza A(H10N3) in a 34-year-old man from Guangdong Province, whose symptoms also began on December 29, 2025.

If confirmed, this would mark only the seventh known human case of H10N3 globally.

According to CHP data, 20 H9N2 cases have been reported in China over the past six months.

Unlike highly pathogenic strains like H5N1, H9N2 has not shown sustained human-to-human transmission.

In the entire year of 2025, mainland China recorded 29 H9N2 cases, which marks a significant increase compared to previous years (11 cases in 2024). 

While global human H9N2 infections remain relatively low, they have risen in recent years, primarily in China, with occasional reports from neighboring regions.

Since the first confirmed human case in 1998 (Hong Kong), officials stress that although H9N2 infections are uncommon in humans, continued surveillance is essential because the virus circulates in poultry and can reassort with other influenza strains.

H9N2 is a low-pathogenic avian influenza virus commonly found in poultry, particularly in live bird markets across parts of Asia. Human infections are generally mild, resembling the seasonal flu, with symptoms such as fever, cough, and sore throat; most patients recover fully without severe complications.

Another virus subtype is notable for causing severe illness in people, despite being classified as low pathogenic in birds. As previously reported, between March 2013 and September 2019, a total of 1,568 human cases of avian influenza A(H7N9) have been reported globally.

As of February 12, 2026, the CHP and the World Health Organization (WHO) (January 2026) say the overall public health risk from these cases is assessed as low. The WHO does not advise special traveller screening at points of entry or restrictions about the current situation of influenza viruses at the human-animal interface

Furthermore, these agencies say vaccination options are currently limited.

According to the Argentine Ministry of Health, there has been an increase in hantavirus cases in early 2026, particularly affecting the Central Region of the country.

This region, which includes provinces such as Buenos Aires, Entre Ríos, and Santa Fe, has consistently reported the highest number of cases in recent seasons.

As of February 2, 2026, national health authorities confirmed a total of 14 cases in the new year, with 7 in Buenos Aires Province, 5 in Salta, 1 in Entre Ríos, and 1 in Río Negro.

The current epidemiological season (from week 27 of 2025 to the present) has shown heightened activity. Argentina has recorded approximately 70 confirmed cases, resulting in 20 deaths, which gives a case fatality rate (CFR) of around 34.5% — the highest rate seen in the past seven years.

The Ministry of Health emphasizes the importance of preventive measures, including avoiding contact with rodents, ensuring proper ventilation in enclosed spaces before entering, using protective gear when cleaning rodent-infested areas, and securely storing food items.

Currently, there is no vaccine for hantavirus. Still, clinical research is focused on DNA and mRNA candidates, with a Phase 2 study evaluating HTNV/PUUV DNA vaccines and new MVA-Hanta trials testing a modified vaccinia Ankara vector. 

Furthermore, treatment is primarily supportive.

Early diagnosis within the critical 48-hour window after the onset of symptoms is essential for improving outcomes. Symptoms typically begin with flu-like signs and can progress to severe respiratory distress.

International organizations, including the Pan American Health Organization, are closely monitoring the situation in this South American country.