Hantavirus: Understanding the Facts

Hantavirus: Understanding the Facts Amid New Global Alerts

By Dr. Serge Gradstein – Family Medical Practice 

In light of recent international reports concerning Hantavirus, it is essential to distinguish between scientific fact and the sensationalism that often follows a global health event. Dr. Serge – Pediatrician with a specialization in Infectious Diseases at Family Medical Practice, provides a comprehensive look at what Hantavirus is, how it behaves, and what the current situation looks like for us here in Vietnam.

What is Hantavirus?

Hantavirus is an RNA virus characterized by a genome divided into three separate loops: Small (S), Medium (M), and Large (L). While this sounds technical, you can think of it simply like shopping for clothes, each segment serves a specific structural purpose.

The virus is protected by a "capsular glycoprotein" which likely determines how the virus attaches to its host and where it settles in the body, specifically whether it affects the nasal mucosa or the lower respiratory tract. This same protein is the primary target for developing antibodies and potential vaccines.

(A) Schematic representation of hantavirus particle, showing three nucleocapsids (L, M and S) and the viral RNAdependent RNA polymerase (RdRp) eclosed in a lipid bilayer envelope carrying the viral glycoproteins Gn and Gc. 
(B) Thinsection electron micrograph of an SNV isolate from the outbreak of HCPS that occurred in the southwestern United States in 1993. Electron micrograph was obtained from the CDC website with permission 

(http://www.cdc.gov/ncidod/diseases/hanta/hps/noframes/hpsem.htm). Adapted from "Recent advances in hantavirus molecular biology and disease," by I. T. M. Hussein et al., 2011, Advances in Applied Microbiology, p. 38.

Global Variations and Transmission

Hantavirus is widespread globally but is generally confined to the rodent community. It typically spills over into humans through accidental heavy exposure to aerosols (tiny airborne particles) contaminated by rodent excretions. 

It is important to understand the two main "worlds" of Hantavirus:

• Old World Variants (Asia & Europe): These primarily cause Hemorrhagic Fever with Renal Syndrome (HFRS). Symptoms can include fever and a drop in platelets (thrombocytopenia), appearing very similar to Dengue fever and with a relatively low mortality.
• New World Variants (The Americas): Identified more recently (since the 1990s), these cause Hantavirus Pulmonary Syndrome (HPS). This often starts like a common cold but can rapidly progress to severe respiratory distress (ARDS). The mortality rate for these variants is high, often exceeding 30%. 

The "Andes" Exception: Human-to-Human Transmission

Most Hantaviruses do not spread from person to person (P2P). However, the ANDES variant, found in South America, is different. As seen in the recent MV Hondius cruise ship outbreak (May 2026) and previous outbreaks in Argentina and Chile, this specific strain has demonstrated the capacity for human-to-human transmission. 

To put this in perspective, we look at the R factor (the number of people one carrier infects):

• Measles or COVID-19: R factor is often > 20.
• Regular Hantavirus: R factor is nearly 0.
• ANDES Variant: Can rise to 5–6 initially but drops to less than 1 once simple preventive steps—like isolation and basic PPE—are taken.

Why Hantavirus is NOT the "Next COVID"

While media reports may cause concern due to the recent Andes variant outbreak, Hantavirus is fundamentally different from SARS-CoV-2:

1. Shedding: COVID-19 infects the entire respiratory tract, and especially the upper respiratory tract, allowing it to spread easily in huge quantities before symptoms even appear. Hantavirus does not shed as easily.
2. Infectivity: Even the "transmissible" Andes variant (R=5) is significantly less infectious than COVID-19 (R>20).
3. Visibility: COVID-19 spreads effectively because many carriers have mild or no symptoms. Hantavirus is much more lethal and symptomatic, making it harder for the virus to spread unnoticed for long periods.

The Situation in Vietnam

Recent studies indicate that Hantavirus is present in about 5% of rodents tested in Vietnam. Interestingly, while there are no reported clinical cases of Hantavirus disease in the country, approximately 3.5% of people tested in rural areas show Hantavirus antibodies, meaning they were exposed to it at some point.

There are two likely reasons for the lack of documented cases:

• A Lack of Awareness: A shortage of specific diagnostic tools may lead to cases being under-reported.
• Misdiagnosis: Because "Old World" Hantavirus looks so much like Dengue (fever and low platelets), it is possible that patients who test negative for Dengue, Zika, or Leptospirosis may actually be experiencing Hantavirus.

Expert Advice

The Hanoi Department of Health and the Ministry of Health have recently increased surveillance at entry points like Noi Bai International Airport as a standard precaution following the cruise ship outbreak in the South Atlantic. 

For the public, the best defense remains simple: rodent control and avoiding cleaning or renovating old and rodent infected locals without proper protection means. By keeping living and working spaces free of rodents, the risk of exposure remains extremely low. At Family Medical Practice, our clinical team continues to monitor these global developments to ensure our patients receive the most accurate and timely diagnostic care.

Watch the Full Interview

For more in-depth insights into the Hantavirus and how it impacts regional health, watch Dr. Serge’s recent interview with Vietnam Today here: https://youtu.be/jE9krASn4U4?si=OtzgdHj_PuyY_F_W 

Dr. Serge Gradstein is an experienced pediatrician and Medical Director at FMP Thao Dien, specializing in children’s health and infectious diseases. With decades of clinical experience, he provides comprehensive pediatric care — from routine health assessments and immunizations to the management of acute and chronic childhood conditions. Dr. Gradstein is fluent in English, French and Hebrew, and is known for his compassionate approach to guiding families through complex health decisions. 

FMP Healthcare Group operates medical centers in major cities including HCMC, Ha Noi and Da Nang, offering consultations with international doctors, check-up centers and emergency ambulance services. 

Visit FMP Thao Dien in Ho Chi Minh City to consult with Dr. Serge Gradstein.

To book an appointment, please call (028) 3744 2000 (FMP - Thao Dien), or email d2.reception@vietnammedicalpractice.com