BQ Journal Vol 53 - Q4 2023 - 23

Morbidity and Mortality Weekly Report
Work Group defined inflammatory neurologic events as cases
of Guillain-Barré syndrome (GBS), chronic inflammatory
demyelinating polyneuropathy, and acute central nervous
system inflammation (e.g., transverse myelitis or acute disseminated
encephalomyelitis [ADEM]) occurring within
42 days after vaccination. The Work Group then employed the
Evidence to Recommendation Framework to guide its deliberations
on recommendation for RSV vaccination, reviewing
data on the public health problem, benefits and harms, value
to the target population, acceptability to key stakeholders,
feasibility, resource use, and equity.§ Work Group conclusions
regarding evidence for the use of RSV vaccines among adults
aged ≥60 years were presented to ACIP at public meetings on
February 23 and June 21, 2023 (10,15).
Vaccine Efficacy and Safety
GSK Vaccine
Evaluated efficacy evidence for the GSK RSV vaccine consisted
of data from one ongoing randomized, double-blind,
placebo-controlled phase 3 clinical trial conducted in 17 countries
and including 24,973 immunocompetent participants
aged ≥60 years randomized 1:1 to receive 1 dose of vaccine
(intervention group, 120 µg preF protein with AS01E adjuvant)
or saline placebo (control group) (20). Efficacy findings were
based on analyses of data collected during May 2021-March
2023, which included two complete RSV seasons for Northern
Hemisphere participants and one complete RSV season for
Southern Hemisphere participants. Efficacy analyses for season
one spanned May 2021-April 2022, while efficacy analyses for
season two spanned August 2022-March 2023; exact studydefined
season dates were site-dependent. Mean time from
vaccination to end of efficacy follow-up across both seasons
was approximately 15 months per participant.
The efficacy of 1 dose of the GSK vaccine in preventing
symptomatic, laboratory-confirmed RSV-associated LRTD¶
was 82.6% (96.95% CI = 57.9%-94.1%) during the first
RSV season and 56.1% (95% CI = 28.2%-74.4%) during
the second season (Table 1).** Efficacy of 1 dose over two
§ Evidence to Recommendation documents are available for the GSK vaccine
(https://www.cdc.gov/vaccines/acip/recs/grade/GSK-Adjuvanted-RSVPreF3adults-etr.html)
and Pfizer RSV vaccines (https://www.cdc.gov/vaccines/acip/
recs/grade/Pfizer-Bivalent-RSVpreF-adults-etr.html).
¶ RSV-associated LRTD (RSVPreF3 trial): two or more lower respiratory
symptoms (new or increased sputum, cough, and dyspnea) or signs (new or
increased wheezing, crackles or rhonchi detected during chest auscultation,
respiratory rate ≥20 respirations per minute, low or decreased oxygen
saturation, and need for oxygen supplementation) for ≥24 hours (including
one or more lower respiratory signs) or three or more lower respiratory
symptoms for ≥24 hours.
** Manufacturer-calculated efficacy. Includes events >14 days after injection and
person-time available from the manufacturer's pivotal phase 3 trial. Estimates
are adjusted for participant age and region.
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US Department of Health and Human Services | Centers for Disease Control and Prevention | MMWR | July 21, 2023 | Vol. 72 | No. 29
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†† Medically attended RSV-associated LRTD (RSVPreF3 trial): LRTD plus
attendance at one or more inpatient or outpatient health care service. Estimates
not included in per-protocol assessments.
§§ Persons with severe RSV illness requiring respiratory support (RSVPreF3
trial): RSV-associated illness requiring oxygen supplementation, positive airway
pressure, or other types of mechanical ventilation. If participant was already
receiving any of these, significant change or adaptation was considered.
¶¶ The limited number of hospitalizations, severe RSV illnesses, and deaths observed
in the trial might have been partially due to limited enrollment of persons at highest
risk for RSV disease including those who were frail, of advanced age, and those living
in long-term care facilities and the exclusion of persons with immune compromise.
The 2021-22 RSV season was also disrupted by the COVID-19 pandemic, and
RSV incidence was lower than expected based on prepandemic surveillance studies.
TABLE 1. Efficacy of 1 dose of GSK respiratory syncytial virus RSVpreF3
vaccine against respiratory syncytial virus-associated disease among
adults aged ≥60 years - multiple countries, 2021-2023
Vaccine efficacy against outcome*
Efficacy evaluation period
Season 1¶
Season 2§§
Combined seasons 1 and 2
(interim)***
RSV-associated
LRTD†
82.6 (57.9-94.1)**
56.1 (28.2-74.4)††
74.5 (60.0-84.5)†††
RSV-associated medically
attended LRTD§
87.5 (58.9-97.6)††
-¶¶
77.5 (57.9-89.0)††
Abbreviations: LRTD = lower respiratory tract disease; RSV = respiratory
syncytial virus.
* Manufacturer-calculated efficacy. Includes events >14 days after injection
and person-time available from the manufacturer's pivotal phase 3 trial.
Estimates adjusted for participant age and region.
† LRTD defined as two or more lower respiratory symptoms (new or increased
sputum, cough, and dyspnea) or signs (new or increased wheezing, crackles
or rhonchi detected during chest auscultation, respiratory rate
≥20 respirations per minute, low or decreased oxygen saturation [<95% or
≤90% if baseline was <95%] and need for oxygen supplementation) for
≥24 hours, including one or more lower respiratory signs, or three or more
lower respiratory symptoms for ≥24 hours.
§ Medically attended RSV-associated LRTD defined as LRTD plus attention at
one or more inpatient or outpatient health care service. Estimates were not
included in per-protocol assessments.
¶ Season 1 vaccine efficacy estimates reflect efficacy against first events
occurring during the first complete RSV season for Northern Hemisphere
participants and a partial first RSV season for Southern Hemisphere
participants (May 2021-April 2022; exact study-defined season dates were
site-dependent).
** 96.95% CI; the CI for primary trial endpoint was adjusted for multiplicity.
†† 95% CI.
§§ Season 2 vaccine efficacy estimates reflect efficacy against first events
occurring during the second complete Northern Hemisphere RSV season
for Northern Hemisphere participants (August 2022-March 2023; exact
study-defined season dates were site-dependent). In addition to Northern
Hemisphere participants, Southern Hemisphere participants were also
included in these analyses, but this time span reflects an interseason period
with low RSV incidence in the Southern Hemisphere.
¶¶ Interim analysis underpowered to estimate efficacy.
*** Combined season 1 and 2 (interim) vaccine efficacy estimates reflect efficacy
against first events occurring any time during Season 1 or Season 2. The
mean time from start to end of efficacy surveillance was approximately
15 months per participant.
††† 97.5% CI; the CI for primary trial endpoint was adjusted for multiplicity.
seasons was 74.5% (97.5% CI = 60.0%-84.5%) in preventing
RSV-associated LRTD and 77.5% (95% CI = 57.9%-89.0%)
in preventing medically attended RSV-associated LRTD.†† The
study was not powered to estimate efficacy against hospitalization
(intervention group = one event; control group = five events), severe
https://www.cdc.gov/vaccines/acip/recs/grade/GSK-Adjuvanted-RSVPreF3-adults-etr.html https://www.cdc.gov/vaccines/acip/recs/grade/GSK-Adjuvanted-RSVPreF3-adults-etr.html https://www.cdc.gov/vaccines/acip/recs/grade/Pfizer-Bivalent-RSVpreF-adults-etr.html https://www.cdc.gov/vaccines/acip/recs/grade/Pfizer-Bivalent-RSVpreF-adults-etr.html
BQ Journal Vol 53 - Q4 2023

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