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Pharmaceuticals2026-05-30 · 9 min read

Rabbit RHDV2 Vaccination: Who Needs It, What It Protects, and What It Does Not Replace

What rabbit owners should know about RHDV2 vaccination in the United States: the Medgene vaccine, booster timing, outbreak risk, and why biosecurity still matters.

Ran Chen
Ran Chen
Founder, VetMedGuide. Life-sciences operator and 10× global market-access lead.
Published

Rabbit hemorrhagic disease virus 2 (RHDV2) kills the majority of rabbits it infects — often with no warning. A rabbit can appear completely normal in the morning and be dead by afternoon. There is no treatment. Vaccination is the only meaningful defense, and the virus is now endemic in the United States.

This article covers what RHDV2 is, how the U.S.-available vaccine works, who should be vaccinated and when, what the booster schedule looks like, what the vaccine does and does not protect against, and why vaccination alone is not the whole safety plan.

What RHDV2 Is and Why It Is Different from Other Rabbit Diseases

RHDV2 is a calicivirus in the genus Lagovirus. The original RHDV (now called GI.1) was first documented in China in 1984 and killed over 140 million domestic rabbits within a year. RHDV2 (genotype GI.2) emerged in France in 2010 and has since spread globally. Unlike classical RHDV, RHDV2 affects a wider host range — including wild cottontails and hares native to North America — and can kill young kits, not just adults.

The virus is extremely hardy in the environment. It survives on contaminated surfaces, in carcasses, on clothing, shoes, hay, feed, and bedding. It spreads through direct contact with infected rabbits, contact with their bodily fluids, through fly and flea bites, and via fomites — any object that can carry the virus from one place to another. Birds and scavengers can transport it. People track it indoors on their shoes.

RHDV2 is not infectious to humans, dogs, cats, or other mammals. It only affects lagomorphs (rabbits, hares, pikas). But for those species, the mortality rate in unvaccinated animals can reach 80–100%.

Clinical signs are often absent until it is too late. Many rabbits are simply found dead. Others may show fever, depression, loss of appetite, respiratory distress, redness of the eyes, or blood-stained nose from internal hemorrhage. Death typically occurs within 12 to 36 hours of infection, though some rabbits survive up to nine days before succumbing.

RHDV2 in the United States: Current Outbreak Status

RHDV2 was first detected in North America in 2016 (in Canada) and appeared in the continental United States shortly after. Since 2020, the virus has been confirmed in domestic and wild rabbits across numerous states, including Arizona, California, Colorado, Nevada, New Mexico, Texas, Utah, Oregon, Minnesota, Wisconsin, Pennsylvania, Connecticut, Illinois, and North Carolina (first confirmed case in Dare County, January 2026).

The USDA maintains an interactive map of affected counties. The virus is now considered endemic in the U.S., meaning it circulates at low levels continuously with periodic outbreaks. Spring and early summer tend to see increased case reports, coinciding with peak wild rabbit populations. California has implemented statewide quarantine and movement restrictions for rabbits and hares entering the state.

Because RHDV2 is classified as a Foreign Animal Disease, suspected cases in domestic rabbits must be reported to state veterinarians. If you find a wild rabbit dead with no obvious cause, do not touch it — contact your state wildlife agency. Multiple dead rabbits in an area can also signal tularemia or plague, which are zoonotic.

The U.S. RHDV2 Vaccine: What It Is and How It Works

The only USDA-licensed RHDV2 vaccine available in the United States is manufactured by Medgene Labs (Brookings, South Dakota). It received Emergency Use Authorization in 2021 and was later granted a conditional license by the USDA Center for Veterinary Biologics.

Vaccine type: Inactivated (killed) recombinant subunit vaccine. It uses a baculovirus vector to produce the VP60 capsid protein of RHDV2. The rabbit's immune system recognizes this protein and develops a protective antibody response. Because the vaccine contains only a protein subunit — not the whole virus — a vaccinated rabbit cannot shed or transmit RHDV2.

Efficacy: In a USDA-approved challenge study, 100% of rabbits that completed the full two-dose series survived direct challenge with live RHDV2 virus. In a published duration-of-immunity study, vaccinated rabbits remained fully protected when challenged six months after the initial series. Related baculovirus-vectored RHDV2 vaccines have shown immunity lasting up to 14 months.

Administration: Subcutaneous injection, given by a veterinarian.

Availability change (mid-2025): The vaccine was originally packaged in 10-dose multi-dose vials, which required clinics to assemble groups of rabbits simultaneously to avoid waste. Since mid-2025, single-dose vials have been available. This change means smaller clinics and general-practice veterinarians can now stock and administer the vaccine during individual appointments rather than requiring dedicated vaccine clinics. If your veterinarian previously could not offer the vaccine, ask again — access has improved significantly.

Who Should Be Vaccinated and When

The House Rabbit Society and exotic-animal veterinary organizations recommend that all domestic pet rabbits be vaccinated against RHDV2. There is no meaningful "low-risk" indoor-only rabbit category in an endemic country. The virus can be tracked indoors on shoes, clothing, groceries, hay, or fresh produce. Indoor rabbits have died from RHDV2 in confirmed outbreaks.

Initial series: Two doses, given 21 days apart. The label specifies the second dose at 21 days, though basic immunological principles suggest a window of 2 to 6 weeks may be acceptable — this is a decision for your veterinarian.

Onset of protection: Full protection develops approximately 14 days after the second dose. A rabbit is not protected after only the first injection.

Minimum age: Consult your veterinarian. The vaccine has been used safely in rabbits as young as 4–6 weeks in outbreak settings, though the labeled age range should be confirmed.

Pregnant and nursing rabbits: Full safety studies in pregnant and nursing animals have not been completed. Discuss the risk-benefit with your veterinarian, particularly if you are in an active outbreak zone.

Previously vaccinated rabbits (with a non-U.S. or imported vaccine): The Medgene vaccine has undergone safety testing consistent with USDA standards. If your rabbit received a different RHDV2 vaccine overseas, discuss revaccination with your veterinarian.

Booster Schedule: What the Evidence Shows

The current recommended booster schedule is:

  • Initial series: Two doses, 21 days apart.
  • First booster: At 6 months after the initial series (per the current label).
  • Annual booster: Every 12 months thereafter, or as directed by your veterinarian based on local outbreak risk.

The label was updated to include a 6-month booster because duration-of-immunity data demonstrated robust protection at 6 months but long-term data beyond that point is still being collected. This is standard for conditionally licensed vaccines — as more data accumulates, the booster interval may be extended.

Why annual boosters matter: The House Rabbit Network and House Rabbit Society both recommend annual boosters. If more than 18 months have elapsed since the last dose, the full two-dose initial series should be restarted. RHDV2 is not a one-time vaccination. It requires ongoing boosters — similar to how rabies vaccination requires periodic revaccination.

Cost: Individual doses typically range from $50–$75 depending on the clinic and region. The initial two-dose series plus an annual booster is a recurring veterinary expense that should be factored into rabbit-owning budgets.

What the Vaccine Does Not Replace

Vaccination significantly reduces the probability of death from RHDV2, but it does not eliminate exposure risk, and it does not protect against anything else that kills rabbits. A vaccinated rabbit still needs the following biosecurity measures:

Indoor housing. Outdoor housing dramatically increases exposure risk. If your rabbit has outdoor playtime, limit it in areas where wild rabbit populations are present. Avoid outdoor housing entirely in counties where RHDV2 has been confirmed in wild rabbits.

Shoe and clothing protocols. Remove shoes before entering your home. Change clothes and wash hands after contact with any rabbit outside your household. Use an RHDV-effective disinfectant (sodium hypochlorite / bleach at proper dilution, or accelerated hydrogen peroxide) on surfaces that may have been contaminated.

Hay and feed sourcing. Source hay and bedding from areas not affected by RHDV2 when possible. Do not feed locally foraged plants, grasses, or branches to your rabbit.

Insect control. Maintain window screens. Minimize fly and mosquito exposure, as these insects can mechanically transmit the virus.

Quarantine new rabbits. Any new rabbit entering the household should be quarantined for at least 14 days, ideally in a separate airspace, before introduction to your existing rabbit(s).

No rabbit playdates. Avoid letting your rabbit interact with rabbits from outside your household. Boarding facilities should be chosen carefully — prefer those that require RHDV2 vaccination for all boarding rabbits.

The vaccine also does not protect against:

  • Myxomatosis (not currently present in the U.S. but a concern in some countries)
  • Pasteurella / upper respiratory infections
  • GI stasis, dental disease, or any other non-RHDV2 condition
  • Other infectious diseases common in rabbits

What to Ask Your Veterinarian Before Vaccination

Before scheduling RHDV2 vaccination, consider these questions:

"Is my rabbit healthy enough for vaccination today?" A rabbit that is already ill — even with something unrelated — may not mount an adequate immune response. Your veterinarian should perform a brief exam before administering the vaccine.

"Do you stock the single-dose vials?" If your veterinarian does not currently offer the vaccine, ask whether single-dose vials are now an option. Many clinics that previously could not justify ordering 10-dose vials can now stock individual doses.

"What is the booster schedule you recommend?" Confirm whether your veterinarian follows the 6-month booster label or a different protocol based on your regional risk.

"What side effects should I watch for?" Reported side effects are typically mild and may include temporary swelling at the injection site, slight fever, and lethargy for 1–2 days. Serious reactions are rare.

"Should I be concerned about other diseases in my area?" Your veterinarian can tell you whether RHDV2 has been confirmed locally, which informs the urgency of vaccination and the biosecurity measures most relevant to your household.

Sources

Topics
Vaccination & Infectious DiseaseEmergency & Critical Care
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