National Center for Emerging and Zoonotic Infectious Diseases

EVIDENCE TO RECOMMENDATIONS FOR 

CHIKUNGUNYA VACCINE USE AMONG 

LABORATORY WORKERS

Susan Hills, MBBS, MTH

CDC Lead, Chikungunya Vaccines Work Group

Arboviral Diseases Branch

Division of Vector-Borne Diseases

Fort Collins, Colorado

ACIP meeting, October 26, 2023
Infections among laboratory workers

 At least 44 chikungunya virus infections identified among laboratory 

workers worldwide over ~ 50 years1–3 

– 43 cases overt disease, 1 asymptomatic infection, no deaths

 4 disease cases in US laboratorians since chikungunya became notifiable 

disease in 2015

– One case hospitalized for observation, no deaths 

 Identified cases underestimate all infections as no formal laboratory 

surveillance system

1. The Subcommittee on Arbovirus Laboratory Safety of the American Committee on Arthropod-Borne Viruses. Am J Trop Med Hyg 1980;

2. Rusnak JM, et al. J Occup Environ Med 2004; 3. US national arboviral disease surveillance system, 2015–2022 
Routes of transmission

 Aerosol 

 Percutaneous

– Needlestick while working with and 

injecting mice

– Forceps prick while dissecting mosquitoes 

infected with chikungunya virus

 Mucosal (possible)
Policy question

Should chikungunya vaccine be recommended for 

laboratory staff at risk for chikungunya virus infection? 
Laboratory worker Evidence to Recommendations notes

 Same GRADE assessment as vaccination for travelers

 Considered data on cross-protection from vaccine against 

3 genotypes of chikungunya virus

– Only limited data from laboratory studies to confirm crossprotection 

– Chikungunya virus considered single serotype and limited 

genotype-specific differences in antigenicity 

– No evidence of re-infection in humans with different genotypes
Evidence to Recommendations: Public health problem

Topic Decision Comment

Public health 

problem

No, not of public health 

importance overall

• Only occasional US laboratory-acquired 

infections reported

• Potential for acute infection with severe 

polyarthralgia and possible chronic 

arthralgia

Values Laboratorians likely think 

desirable effects large relative to 

undesirable effects 

No important variability

• Scientists will understand risks of disease 

and risks and benefits of vaccination
Evidence to Recommendations: Public health problem

Topic Decision Comment

Public health 

problem

No, not of public health 

importance overall

• Only occasional US laboratory-acquired 

infections reported

• Potential for acute infection with severe 

polyarthralgia and possible chronic 

arthralgia

Values Laboratorians likely think 

desirable effects large relative to 

undesirable effects 

No important variability

• Scientists will understand risks of disease 

and risks and benefits of vaccination
Evidence to Recommendations: Acceptability

Topic Decision Comment

Acceptability Yes, acceptable to key 

stakeholders

• Acceptable for occupational health 

directors, laboratory managers, and 

laboratorians because will improve safety

Resource use Yes, reasonable and efficient 

allocation of resources

• Limited number of staff undertaking 

research or specific diagnostic work with 

chikungunya virus

• Small cost to avoid impact and costs of 

worker becoming infected

Equity Probably increased • If employer offers vaccination, will 

improve safety for staff and addresses an 

occupational health issue
Evidence to Recommendations: Resource use

Topic Decision Comment

Acceptability Yes, acceptable to key 

stakeholders

• Acceptable for occupational health 

directors, laboratory managers, and 

laboratorians because will improve safety

Resource use Yes, reasonable and efficient 

allocation of resources

• Limited number of staff undertaking 

research or specific diagnostic work with 

chikungunya virus

• Small cost to avoid impact and costs of 

worker becoming infected

Equity Probably increased • If employer offers vaccination, will 

improve safety for staff and addresses an 

occupational health issue
Evidence to Recommendations: Equity

Topic Decision Comment

Acceptability Yes, acceptable to key 

stakeholders

• Acceptable for occupational health 

directors, laboratory managers, and 

laboratorians because will improve safety

Resource use Yes, reasonable and efficient 

allocation of resources

• Limited number of staff undertaking 

research or specific diagnostic work with 

chikungunya virus

• Small cost to avoid impact and costs of 

worker becoming infected

Equity Probably increased • If employer offers vaccination, will 

improve safety for staff and addresses an 

occupational health issue
Evidence to Recommendations: Feasibility

Topic Decision Comment

Feasibility Yes, feasible • Likely build on existing occupational 

health program
Balance of consequences

o Undesirable 

consequences 

clearly 

outweigh

desirable 

consequences 

in most 

settings

o Undesirable 

consequences 

probably 

outweigh 

desirable 

consequences 

in most 

settings

o The balance 

between 

desirable and 

undesirable 

consequences is 

closely balanced 

or uncertain

o Desirable 

consequences 

probably 

outweigh 

undesirable 

consequences 

in most settings

o Desirable 

consequences 

clearly 

outweigh 

undesirable 

consequences 

in most settings

o There is 

insufficient 

evidence to 

determine the 

balance of 

consequences
Draft recommendation 

Chikungunya vaccination is recommended for laboratory 

workers with potential for exposure to chikungunya virus
Information accompanying recommendations

 Local biosafety committee should undertake risk assessment 

of potential for chikungunya virus exposure considering 

– Type of work to be performed 

– Biosafety level at which work is being conducted

 Vaccination not necessary for workers handling routine clinical 

samples 
Draft recommendation 

Chikungunya vaccination is recommended for laboratory 

workers with potential for exposure to chikungunya virus