Vaccine News

The São Paulo State Health Department recently confirmed that Dengue is a seasonal disease. During the rainy season, a high transmission rate can be observed. Throughout Brazil, Dengue is the most critical arbovirus disease transmitted by arthropod vectors.

Over the past 25 years, nearly 18 million Brazilians have been infected with Dengue.

As of May 26, 2025, the state of São Paulo, with a population of 44 million, has reported about 617,000 of Brazil's 2.5 million Dengue cases this year. According to data, the state of São Paulo leads in the number of deaths from dengue fever, with 692 cases.

In February 2025, a public health emergency was declared to alert residents and international visitors of this continuing health risk.

Last year, about 2.1 million Dengue cases and 2,100 related fatalities were reported in São Paulo.

This ongoing surge is related to Dengue virus serotype 3 (DENV-3) reemergence since the population is not immunized against this serotype.

While a second-generation Dengue vaccine will be limited in availability in 2025, Butantan Institute in São Paulo has been involved in developing an innovative vaccine that could become available in 2026.

Additionally, with the annual influenza season arriving in South America, beginning on May 27, 2025, the flu vaccination will be offered to the entire population in São Paulo's 645 municipalities over six months of age.

When visiting Brazil in 2025, the U.S. CDC recommends international travelers speak with a travel vaccine expert about various immunization options, such as chikungunya and yellow fever.

When the polio eradication campaign was launched in 1988, the ambitious goal was to eliminate the disease by 2000. Despite the campaign's remarkable progress, polio remains a global health challenge in 2025.

According to the World Health Organization (WHO), polio remains a global health concern in May 2025.

The WHO says there is no cure for polio, and infection prevention through vaccination is the best protection available. 

Polio paralysis is caused by a human enterovirus called the wild poliovirus. However, less than 1% of wild poliovirus infections result in paralysis.

An article published in Clinical Infectious Diseases on May 21, 2025, says one significant misstep of the polio vaccination was the transition from the trivalent oral polio vaccine (OPV) to the bivalent OPV, which excluded the type 2 vaccine. 

This switch occurred after the eradication of wild-type 2 poliovirus was declared in 2015.

This change was made to curb the emergence of circulating vaccine-derived polioviruses (cVDPV), which occur when the weakened virus in the vaccine mutates back to virulence and spreads in under-immunized populations.

Contrary to the optimistic modeling predictions, the exclusion of type 2 vaccine led to a dramatic increase in cVDPV cases, skyrocketing from just 6 cases in 2016 to more than 1,000 cases 3 years later, with more than 3,300 children paralyzed since the switch in 43 countries.

These researchers believe that the Inactivated Polio Vaccine (IPV) must be an essential part of polio eradication campaigns in the future.

Today, the U.S. CDC is partnering with other agencies through the Global Polio Eradication Initiative (GPEI) to help eradicate polio globally. Last week, the GPEI reported that Germany, Nigeria, Papua New Guinea, and Sudan confirmed cVDPV2-positive environmental samples and human infection.

As of April 2025, the CDC identified 38 countries reporting poliovirus detections.

In the U.S., vaccinations with the IPV are standard with the CDC's schedules, including a booster dose for certain people visiting poliovirus outbreak areas in 2025.

'Before any international travel, make sure you are up to date on your polio vaccines,' says the CDC.

As of May 25, 2025, polio vaccination services are offered at clinics and pharmacies nationwide.

While most rabies cases in the United States are related to bites from infected bats, not dogs, a recent report from rural North Carolina indicates that trend may be changing.

According to City of Roxboro officials, on May 20, 2025, a man was attacked by a coyote in the area of Somerset Drive. Local media reported that the man could defend himself and kill the coyote. 

The Person County Animal Services seized the dead coyote for rabies testing.

The County says, 'If you see wildlife behaving strangely, primarily nocturnal animals such as skunks and raccoons found during daylight hours, do not approach the animal. Instead, call 336-597-0545 and speak to the Animal Control Officer.'

'If any animal bites you, wash the wound immediately with soap and water and seek medical attention.'

Additionally, rabies vaccination is recommended for various reasons.

At the end of March 2025, a bat found in the area of Shady Oak Road in northern Person County tested positive for rabies, becoming the second confirmed case in Person County this year.

The U.S. CDC says rabid dogs kills about 70,000 people worldwide. Many countries have not looked for rabies in local wildlife, and it is likely that yet-undetected wildlife also maintain the virus, and are a threat to unaware international travelers.

Certain vector-borne diseases, such as Chikungunya, Dengue, and Zika, are expanding public health challenges in Southeast Asia, including the Kingdom of Thailand. There has been evidence of chikungunya virus transmission in Thailand within the last five years.

These diseases have become a health risk to Thailand's 35 million visitors annually.

A research article published in the Journal of Infectious Diseases on May 21, 2025, assessed the role of sylvatic reservoirs in arboviral circulation by examining serological evidence of exposure to DENV, ZIKV, and CHIKV among humans and macaques living close in endemic regions. 

The overall seropositivity rates across arboviruses among human populations are higher than those of macaques (38.5-74.4% versus 0-8.0%, respectively).

Globally, a study published in April 2025 estimates that 5.66 billion (95% confidence interval 5.64-5.68) people currently live in areas suitable for Dengue, Chikungunya, and Zika.

The U.S. CDC says international travelers should speak with a vaccine expert before visiting Thailand in 2025 regarding routine and travel vaccine options, such as Valneva SE's IXCHIQ® Chikungunya vaccine. These vaccines are offered at travel clinics and pharmacies and should be administered weeks before departing abroad in 2025.

With the mosquito-transmitted Chikungunya virus infecting over 144,000 residents and international travelers throughout the Region of the Americas in 2025, access to an approved vaccine may soon expand.

According to Valneva SE's website, on May 23, 2025, Valneva wrote, 'By 2026, we want to enable access to Valneva's single-shot chikungunya vaccine IXCHIQ® in India and Brazil by enabling local manufacturing and access through technology transfers.'

'In Asia, we signed an exclusive license agreement with the Serum Institute of India, complementing our existing agreement with Instituto Butantan in the Americas.'

IXCHIQ was the first vaccine approved in 2023 to address chikungunya virus infections in adults at increased risk of exposure to the mosquito-transmitted disease. This vaccine is currently available in the United States at clinics and pharmacies.

The U.S. CDC has issued travel health notices for outbreaks in Mauritius, Mayotte, Réunion, Somalia, and Sri Lanka to warn international travelers of the Chikungunya health risk. Vaccination is recommended for travelers visiting an area with an outbreak.

The U.S. FDA published the Briefing Document for the Vaccines and Related Biological Products Advisory Committee (VRBPAC) meeting on May 22, 2025. VRBPAC has met multiple times since 2022 to discuss and make recommendations on selecting the strain compositions for COVID-19 vaccines.

Today's meeting agenda focused on selecting the 2025-2026 Formula for COVID-19 Vaccines.

As noted in the Document, while current circulating SARS-CoV-2 variants have derived from the JN.1 variant that appeared in late 2023, the JN.1 virus lineage continues to evolve.

The LP.8.1 subvariant has now become the predominant circulating strain, but other virus subvariants including LF.7 and XFG have also been increasingly detected in the U.S. in the recent weeks.

Because of the continuing antigenic drift between JN.1 and KP.2, which were used in the 2024-2025 vaccine, and the currently circulating subvariants in the Asia Pacific countries, a review and discussion regarding the need for a strain composition update for COVID-19 vaccines is warranted.

In an article published in the New England Journal of Medicine on May 20, 2025, FDA Commissioner Dr. Martin Makary and Dr. Vinay Prasad, director of the FDA's Center for Biologics Evaluation and Research, stated that these changes align the U.S. with the practices of many other countries.

'The FDA's new COVID-19 philosophy represents a balance of regulatory flexibility and a commitment to gold-standard science. The FDA will approve vaccines for high-risk persons and, at the same time, demand robust, gold-standard data on persons at low risk.'

'These clinical trials will inform future directions for the FDA, but more importantly, they will provide information that health care providers and the American people desperately crave.'

The complete FDA Briefing Document is available at this link.

Over the past few weeks, COVID-19 cases have surged across Asia, with Hong Kong and Singapore reporting spikes.

The current COVID-19 infection wave is unfolding as the annual respiratory season usually subsides. It has been linked to the JN.1 variant, which was first identified in 2023.

However, as of May 21, 2025, health officials in India believe they have the situation under control.

India's Ministry of Health and Family Welfare (MoHFW) recently stated that 'the current situation in India is “under control,” with only 257 active cases reported.'

This latest resurgence of COVID-19 is a real-world reminder that the SARS-CoV-2 coronavirus remains a public health threat worldwide.

When visiting India in May 2025, the U.S. CDC writes, ' All eligible travelers should be up to date with their COVID-19 vaccines.'

Additionally, the CDC suggests routine vaccinations and says there has been evidence of chikungunya virus transmission in India within the last 5 years. Cholera is also presumed to be present in India, and Japanese encephalitis vaccination is recommended when visiting endemic areas.

These travel vaccines are offered in the U.S. at clinics and pharmacies.