Is 2 months too late for rabies vaccine?

Rabies is a serious viral infection that affects the central nervous system. It is almost always fatal once symptoms appear. However, rabies can be prevented through prompt treatment after exposure. An important part of rabies post-exposure prophylaxis is receiving the rabies vaccine. This raises the question – is 2 months too late to receive the rabies vaccine after a potential rabies exposure?

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What is rabies and how is it transmitted?

Rabies is caused by the rabies virus. It is spread through the saliva of infected animals, usually through bites. In rare cases, it can be spread through scratches, open wounds, or mucous membranes contaminated with saliva from an infected animal. The rabies virus travels to the central nervous system, causing inflammation of the brain and spinal cord. Once symptoms appear, rabies is almost always fatal.

Rabies can be transmitted by all mammals, but it is most commonly spread by dogs, bats, raccoons, skunks, and foxes in the United States. Worldwide, dogs are the most common source of human rabies deaths. Rabid animals usually exhibit strange behavior – difficulty swallowing, excess salivation, aggression, restlessness, and neurological symptoms. However, rabies can only be definitively diagnosed by laboratory testing after death.

What is the rabies vaccine and how does it work?

The rabies vaccine works by stimulating the body’s immune system to produce antibodies against the rabies virus. There are several rabies vaccines available:

Human diploid cell vaccine (HDCV)
Purified chick embryo cell vaccine (PCEC)

Rabies vaccine adsorbed (RVA)
Rabies vaccine absorbed (RVA)

These vaccines are given as a series of shots, usually 4 doses given over 14 days. The first dose primes the immune system, while the subsequent doses provide further stimulation to generate protective antibodies. The antibodies neutralize the rabies virus, preventing it from infecting cells and causing disease.

Rabies post-exposure prophylaxis

Rabies post-exposure prophylaxis (PEP) refers to the immediate treatment given after a suspected rabies exposure, before symptoms occur. Prompt PEP is highly effective at preventing rabies. There are two main components:

Rabies immune globulin (RIG) – provides immediate short-term protection by injecting rabies antibodies directly into the wound and surrounding area.
Rabies vaccine – provides long-term protection by stimulating the body’s immune response to generate rabies antibodies.

In the United States, the rabies vaccine series is given over 14 days as:

First dose: As soon as possible after exposure
Additional doses: 3, 7, and 14 days after the first dose.

Timely vaccination is critical for PEP to be effective. After a bite, the rabies virus travels slowly through nerves up to the brain. It can take weeks or months before symptoms begin. Vaccination during this incubation period allows time for antibodies to develop and neutralize the virus before it reaches the brain. This prevents the infection from becoming established and causing disease.

Is 2 months too late for the rabies vaccine?

Generally, yes – 2 months is too late to receive the rabies vaccine after an exposure. Here’s why:

The incubation period before rabies symptoms appear is extremely variable, ranging from less than a week to several years. But most cases occur within 1-3 months after a bite.

Waiting 2 months misses the critical window for timely vaccination soon after exposure. At this point, the rabies virus may have already reached the brain and begun to replicate.
While rabies vaccination can still be given, it is less likely to be effective at this late stage. Antibodies may not have time to develop and control the infection before symptoms start.
Once clinical symptoms of rabies appear, it is almost always fatal, even with intensive care. At that point, treatment is mainly palliative.

That being said, giving the vaccine 2 months after exposure is still recommended, even if less effective. In rare cases, it may still provide some protective benefit when the incubation period is prolonged.

Are there any exceptions?

There are a few exceptional cases where rabies vaccination may still be warranted beyond 2 months:

Unclear exposure: If it is unclear whether an exposure occurred or when it happened, vaccine may be given up to 6 months later as a precaution.

Delayed treatment: If PEP was delayed for some reason, vaccination may still provide benefit if given before symptoms start.
Ongoing high risk: For people at continued high risk of rabies exposure, such as laboratory workers, vaccines could provide some protection despite the delay.

However, these situations should be evaluated on a case-by-case basis by a healthcare provider. The benefits become less certain the longer vaccination is postponed. Ultimately, timely PEP soon after an exposure gives the greatest chance of preventing rabies.

What if I’m 2 months late for the vaccine?

If it has been more than 2 months since a potential rabies exposure and you have not received PEP:

Contact your healthcare provider immediately. Let them know the details of the exposure (when, what animal, bite vs scratch, etc).
Be evaluated to determine your individual risk. Factors like type of exposure, animal behavior, and rabies activity in the area affect risk.

Discuss if delayed vaccine may still be worthwhile in your case, or if close monitoring for symptoms is recommended instead.
If vaccine is given this late, receive the full PEP series (4 doses over 14 days).
Follow instructions to report any suspicious symptoms to seek medical care immediately.

Unfortunately, when 2 months have passed, your chance of developing rabies may now mainly depend on factors like the nature of the exposure and virus transmission. But contacting a healthcare provider promptly gives you the best chance for evaluation and possible late vaccination if appropriate.

How effective is the rabies vaccine when delayed 2 months?

The effectiveness of rabies vaccination decreases the longer it is delayed past the ideal PEP window:

Within 7 days: Nearly 100% effective

7-21 days: Very high efficacy still when full series is given
21-35 days: Reasonable efficacy in most cases
2-3 months: Uncertain, possibly low efficacy

Unfortunately, there is limited data beyond 6 weeks. But based on rabies virus pathology, vaccine likely has low effectiveness at 2 months or later after exposure. Unlike timely PEP, late vaccination may not prevent rabies in most cases.

However, it is impossible to predict efficacy in a given individual. Some people may still mount an antibody response sufficient for protection when vaccinated late. But this chance declines as more time passes. This underscores the importance of prompt PEP whenever a rabies exposure occurs.

What are the risks of delaying the rabies vaccine?

Delaying rabies vaccination past the recommended timeframe has serious risks:

Rabies developing: The main risk is that rabies can develop and progress to a fatal disease state. Timely vaccination soon after an exposure is key to preventing this.
Treatment becoming ineffective: As time passes, the vaccine may no longer be able to stimulate protective immunity fast enough to get ahead of disease progression.
Symptoms being missed: The early symptoms of rabies are non-specific, like fever, headache, and malaise. They can easily be mistaken for other conditions, leading to delayed treatment.

Death: Once clinical rabies manifests, survival is extremely rare, even with intensive care. Rabies has a mortality rate over 99% at this stage.

For these reasons, PEP should never be delayed when a known rabies exposure occurs. Even waiting just a few weeks can be the difference between life and death with this serious infection.

Can you get the rabies vaccine after symptoms start?

Unfortunately, getting the rabies vaccine after symptoms start is not effective or recommended. At this point, the infection is established in the central nervous system and actively replicating. Vaccination does not clear the virus or alter disease progression once symptoms are present.

Some key points:

Vaccination aims to prevent the virus from infecting the CNS and causing disease. It does not treat active rabies infection.
The rabies virus has likely already reached the brain if clinical signs are apparent.

Antibodies do not cross into the CNS well to clear a central nervous system infection.
Symptomatic rabies infection has an extremely high fatality rate, even with the best available care.

Instead, the focus shifts to comfort-directed care once rabies symptoms manifest. Sedatives, pain management, hydration, anticonvulsants, and other palliative measures may be used. But the prognosis at this point is unfortunately grave.

How long does rabies vaccine immunity last?

After receiving the full pre- or post-exposure rabies vaccine series, immunity generally lasts for years. Some key points on rabies vaccine immunity duration:

Pre-exposure vaccination provides protective antibody levels for at least 2-3 years, likely much longer.
One study found detectable rabies antibodies in 96% of people 10 years after pre-exposure vaccination.

Post-exposure vaccination also confers long-lasting immunity, likely lifelong in most cases.
Those at continuous risk should have antibody testing done every 6 months to 2 years to determine if a booster is needed.
Routine periodic boosters are no longer recommended except based on antibody testing.

In most cases, people do not need to repeat the full vaccine series unless they experience another high-risk rabies exposure. But prompt post-exposure prophylaxis, including vaccine, should still be sought after any suspected rabies contact, even in those previously immunized.

Can you get rabies if vaccinated?

It is extremely rare but possible in some cases to develop rabies even after receiving the rabies vaccine. This may happen in the following scenarios:

Incomplete vaccination: If the full multi-dose vaccine series is not completed promptly, immunity may be inadequate to prevent rabies.

Very short incubation period: If symptoms start less than 7 days after exposure, there may not have been enough time to develop protective antibodies.
Immune deficiency: People with weak immune systems may not generate sufficient antibodies even after vaccination.
High viral load: Large amounts of virus in the inoculum, as with severe bites to highly innervated areas like the head and neck, may overwhelm immunity.

However, these cases are atypical. When the rabies vaccine series is administered properly and promptly after exposure, it is nearly 100% effective at preventing disease in most individuals.

Can you delay the rabies vaccine schedule?

It is not recommended to alter the rabies vaccine schedule, as the 4 doses over 14 days are timed to induce prompt immunity. However, some delays may be unavoidable.

If a dose is delayed by a few days, it can be administered and the series continued.

For delays over 1 week, the series should be restarted for full efficacy.
The final dose should be given by day 28, or the entire series restarted.
Never immunize within the minimum 3 day interval between doses.

While well-timed vaccination is optimal, doses given late or with minor delays can still offer some level of antibody protection against rabies in most cases.

What should I do if I miss a rabies vaccine dose?

If you miss or delay a rabies vaccine dose:

Notify your healthcare provider as soon as possible.

Complete the postponed dose as close as feasible to the recommended schedule (days 3, 7, and 14).
If delayed more than a week, restart the series for best results.
Never get rabies vaccine shots within 3 days of each other.

Consider antibody testing 2-4 weeks after the final dose to confirm a protective titer was reached.
Immediately report any symptoms like fever, neurological changes, or unusual behavior to seek medical care in case PEP failed.

Adhering strictly to the rabies vaccine schedule is ideal. But rabies can still be prevented in most cases as long as all doses are ultimately received, even if briefly delayed.

Should I get the rabies vaccine just in case?

The rabies vaccine should only be given in cases where there is a reasonable probability of exposure. Routine “just in case” vaccination is not recommended or necessary in most situations.

Pre-exposure rabies vaccine is appropriate for:

Travelers spending extensive time in remote areas where rabies is endemic

Veterinarians, animal handlers, and others at occupational risk
Laboratory workers handling live rabies virus
Persons living in or frequently traveling to locations with poor access to rabies PEP

For the average person living in an area like the U.S. with good medical care accessibility, the risks do not warrant routine pre-exposure prophylaxis outside of the above indications.

The vaccine is very safe but not entirely without risks or cost. Reactions like local pain, fever, headaches, nausea, and hypersensitivity, though uncommon, are possible. Giving it without a specific probable exposure or risk factor goes against the medical principle of only using interventions when the benefit clearly outweighs potential harm.

Talk to your healthcare provider if you may have an elevated occupational, travel, or other rabies risk warranting consideration of pre-exposure vaccination.

Conclusion

In most cases, 2 months is too late for the rabies vaccine to provide effective post-exposure prophylaxis after a suspected contact with a rabid animal. While the vaccine may still be given as a precaution, it is unlikely to prevent rabies at this late stage. The key is prompt vaccination within 7 days, and ideally within 24 hours, of any possible rabies exposure. This allows time for protective antibodies to develop during the rabies virus incubation period before it can spread to the central nervous system and cause fatal disease. Delaying PEP places an individual at high risk of developing severe, incurable rabies infection. Anyone who experiences a potential rabies contact should immediately seek medical care for risk assessment and timely administration of rabies immune globulin and vaccine for the greatest chance of preventing this serious and fatal illness.