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ACIP meeting focuses on pertussis, influenza, Ebola, measles, and more

ACIP meeting focuses on pertussis, influenza, Ebola, measles, and more

Immunization Update

Stephan L. Foster, PharmD, FAPhA, CAPT (Ret)

Syringe and First-Aid Cross symbols within a shield.

CDC’s Advisory Committee on Immunization Practices (ACIP) met in Atlanta on October 23–24, 2019, to discuss the current influenza season and vaccine effectiveness; updated recommendations for pertussis, Ebola, orthopoxvirus, dengue, and rabies vaccines; measles outbreaks; and a variety of other immunization topics.

Adult and childhood immunization schedule

The 2020 immunization schedules have been updated to reflect the changes ACIP has made over the last year. There were no structural changes except the addition of a blue color for shared clinical decision making and a grey color for no recommendation or not applicable. 

Pertussis

Current recommendations are for Tdap as a single dose followed by Td every 10 years; a single dose of Tdap for wound management followed by Td for completion of the series; and a single dose of Tdap for catch-up for persons aged 7 years and older. 

There are limited data on the safety of multiple doses of Tdap, and several published studies have shown no statistically significant differences in local or general symptoms when using Tdap compared with Td for repeat doses. Also, the Vaccine Adverse Events Reporting Systems and the Vaccine Safety Datalink have not reported an increase in adverse events with Tdap compared with Td when looking at closely spaced Tdap doses.

Given this information, the work group consensus was that either Td or Tdap can be used for catch-up immunization of persons aged 7 years and older, both in the general population and in pregnant women. Children aged 7 to 9 years will need another dose at age 11 to 12 years; however, if the dose was given at age 10 years, there is no need to repeat at age 11 to 12 years. 

The work group recommended that either Td or Tdap be used for the decennial booster, and tetanus prophylaxis for wound management and for catch-up. ACIP voted to approve the changes to the recommendations.

Influenza

Although multiple influenza serotypes circulated in the southern hemisphere during the past year, ACIP reported that the number of cases in the northern hemisphere are few, and it is too early to draw definite conclusions. 

For the few cases that have been laboratory confirmed, the A(H1N1) circulating viruses are similar to the vaccine strain as well as the B/Yamagata circulating strain. Several different A(H3N2) and B/Victoria serotypes with a partial match to the vaccine strains are circulating. 

Influenza activity is low at this time but starting to rise, and it is too early to characterize what strain will be predominately circulating. Vaccine supply is comparable to that of previous seasons. 

Sanofi-Pasteur presented data showing that local and systemic reactions to high-dose quadrivalent vaccine were similar to those of high-dose trivalent vaccine in Phase III studies. Immunological response, as measured by antibody geometric mean concentrations and seroconversion rates, demonstrated a noninferior response. This vaccine will be evaluated by FDA with the hope that it will be available for the 2020–2021 influenza season.

ACIP addressed concerns about the higher influenza hospitalization rates in patients older than 65 and the ongoing efforts to improve vaccine effectiveness in this age group. Currently, eight influenza vaccine products are available for older adults; ACIP does not make any specific recommendation for one vaccine over another. 

Vaccine effectiveness and relative effectiveness of the different vaccines vary from season to season; thus, there also is no certainty that results of any studies on these vaccines would carry across different influenza seasons. CDC plans to do a meta-analysis on the vaccines used in persons older than 65 compared with other available vaccines over the next influenza season.

Ebola

On August 1, 2018, an outbreak of Ebola virus (EBV) disease occurred in the Eastern Demographic Republic of Congo, and as of September, there have been more than 3,000 cases (including 165 health care workers), with 2,000 deaths. Of six Ebola species, Zaire ebolavirus has been responsible for 64% of the outbreaks since 1976. 

EBV can be transmitted in all body fluids and is spread by direct contact, with incubation periods of between 2 and 21 days and death in most cases by 7 to 10 days. Natural immunity duration is unknown and postulated to be species specific, and there is no known immune correlate for protection. 

Eleven cases have occurred in the United States, with seven medically transferred here for care and four diagnoses made in the United States. Two of the 11 patients died. The patients were eventually treated at Special Pathogen Treatment Centers; however, three were treated initially at community hospitals.

Populations at potential risk are laboratory personnel, health care workers, and outbreak responders. An investigational vaccine (rVSV-ZEBOV) has been used in a ring vaccination strategy. The ring strategy offers vaccination first to contacts to the confirmed case, the second ring to contacts of contacts, and the third ring to persons who could be exposed, such as those who live in the community, health care personnel, and other responders. 

A ring vaccination trial completed in 2017 for the Ebola vaccine (rVSVΔG-ZEBOV-GP, live, attenuated) V920 (Merck) showed 100% vaccine efficacy 10 days or more postvaccination. Immunogenicity and safety studies showed durability of titers 18 months’ postvaccination, with a good safety profile.  

Merck plans to seek an indication for adults 18 years and older, with other groups added as the studies are completed. ACIP will consider policy options pending vaccine licensure, potentially in February 2020.

Measles

Measles outbreaks continue in the United States and worldwide. As of October 19, 2019, a total of 1,250 cases have been reported in the United States, the largest number since 1992. There have been 13 outbreaks, with 6 in underimmunized communities. More than 75% of the cases this year are linked to outbreaks in New York, and 74% of patients in these cases were unvaccinated.

The New York Health department used the following measures to control the outbreak:

  • Notification of exposed contacts
  • Postexposure prophylaxis with MMR or IG
  • Home isolation
  • Outreach
  • Community engagement
  • Press releases
  • Print ads and social media
  • Removal of daycare and school exclusions
  • Emergency order requiring vaccination
  • MMR vaccination

The New York outbreak was declared over on October 3, 2019, following two incubation periods (42 days) without cases.

Dengue

Dengue continues to be one of the most important viruses worldwide, including in Puerto Rico, U.S. Virgin Islands, American Samoa, and some affiliated Pacific Island nations. 

Denvaxia (Sanofi-Pasteur), a tetravalent, live-attenuated viral vaccine, was approved in May 2019. As mentioned in the last ACIP report, vaccine efficacy varies by age, dengue serotype, disease severity, and previous natural infection.  Though the vaccine reduced severe disease and hospitalization among 9- to 16- year-olds, it caused an increased risk of hospitalization in 2- to 5-year-olds. This is thought to be due to previous exposure to natural dengue in the older children. 

The vaccine, administered in three doses 6 months apart, is indicated in individuals ages 9 to 16 years living in endemic areas with laboratory-confirmed previous dengue infections. It is not to be used in persons not previously infected by any dengue serotype, as assessed through medical record of a previous laboratory-confirmed dengue infection or through serological testing.

A GRADE analysis based on published and unpublished data resulted in the following conclusions:

  • For seropositives, there is high-quality evidence of benefit for virologically confirmed dengue, hospitalization, and severe dengue with no harm.
  • Among seronegatives, the evidence level is lower, and there is a signal of increased risk among those receiving the vaccine.

Because the sensitivity and specificity of the laboratory test, as well as disease incidence rate, can affect cost effectiveness, high-level screening will be important. In addition, changes in the cost of hospitalizations and this screening can affect cost effectiveness. These will be important factors in a future ACIP recommendation.

Rabies

Despite the current shortage of rabies vaccine and immune globulin, sufficient supply of both exists to meet demand. There are two to four U.S. rabies cases each year, mostly due to domestic and international exposure, and there have been no occupational exposures over the last 10 years. About 5,000 animals test positive for rabies in the United States each year, and 50,000 people receive postexposure prophylaxis. 

Various administration schedules, as well as different types of vaccines, have been used over the last century since a vaccine was developed by Louis Pasteur in 1885. 

Currently, a three-dose cell-cultured vaccine is recommended in the United States. Intradermal and I.M. routes are used worldwide, with the decision on which to use based on vaccine sparing in limited supply settings.

A new two-dose series given 7 days apart is now recommended by the World Health Organization, but the duration of immunity of this schedule has not been evaluated. Also, a few studies are available that show some anamnestic responses. 

Booster recommendations have been based on the degree of risk in the person, but studies have not been performed to show if this is valid, and data are scarce in immunocompromised persons and pregnant women. The work group is now re-evaluating the data to update the recommendations.

Orthopoxvirus

FDA has licensed a new vaccine for orthopoxvirus prevention, Jynneos (Bavarian Nordic). Orthopoxviruses include smallpox, for which the vaccine is indicated. Jynneos is an attenuated, live, replication-deficient vaccinia virus that can be used in persons for whom ACAM2000 is contraindicated. The work group will begin to review these data and update the ACIP recommendations over the next 2 years.

Full minutes of the ACIP meeting are available on the CDC website.

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Posted: Jan 7, 2020,
Categories: Drugs & Diseases,
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