Observatory and Fast Facts

Oct. 19, 2022

New recommendations for the composition of influenza vaccines in 2023

The World Health Organization has announced the recommended viral composition of influenza vaccines for the 2023 southern hemisphere influenza season.

The recommendations issued will be used by national vaccine regulatory agencies and pharmaceutical companies to develop, produce, and license influenza vaccines. The periodic update of viruses contained in influenza vaccines is necessary for the vaccines to be effective due to the constantly evolving nature of influenza viruses. 

The recommendation is based on the advice of a group of experts from WHO Collaborating Centres and WHO Essential Regulatory Laboratories that analyze virus surveillance data generated by the WHO Global Influenza Surveillance and Response System (or GISRS).

Around a billion people get seasonal influenza every year and the threat of an influenza pandemic is ever-present. For this reason, the need to monitor circulating respiratory viruses, including influenza, continues to be critical. This monitoring informs the vaccine composition recommendations that WHO issues twice a year.


WHO recommends that quadrivalent vaccines for use in the 2023 southern hemisphere influenza season contain the following: 

Egg-based vaccines

an A/Sydney/5/2021 (H1N1) pdm09-like virus;

an A/Darwin/9/2021 (H3N2)-like virus;

a B/Austria/1359417/2021 (B/Victoria lineage)-like virus; and

a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

Cell culture- or recombinant-based vaccines

  • an A/Sydney/5/2021 (H1N1) pdm09-like virus;
  • an A/Darwin/6/2021 (H3N2)-like virus;
  • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus; and
  • a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.

WHO recommends that trivalent vaccines for use in the 2023 southern hemisphere influenza season contain the following:  

Egg-based vaccines

  • an A/Sydney/5/2021 (H1N1) pdm09-like virus;
  • an A/Darwin/9/2021 (H3N2)-like virus; and
  • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.

Cell culture- or recombinant-based vaccines

  • an A/Sydney/5/2021 (H1N1) pdm09-like virus;
  • an A/Darwin/6/2021 (H3N2)-like virus; and
  • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus

Findings suggest COVID-19 rebound not caused by impaired immune response

Findings from a small study of eight patients published in Clinical Infectious Diseases suggest that COVID-19 rebound is likely not caused by impaired immune responses.

The study, led by scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, aimed to define the clinical course and the immunologic and virologic characteristics of COVID-19 rebound in patients who have taken nirmatrelvir/ritonavir (Paxlovid), an antiviral therapeutic developed by Pfizer, Inc. COVID-19 rebound is characterized by a recurrence of COVID-19 symptoms and/or a new positive viral test after having tested negative, according to the Centers for Disease Control and Prevention. According to the study authors, the results do not support the hypothesis that the five-day course of Paxlovid is too short for the body to develop a strong immune response to SARS-CoV-2, the virus that causes COVID-19.

Participants were selected from adults enrolled in an ongoing COVID-19 study at the NIH Clinical Center in Bethesda, Maryland, and other local hospitals. The study aims to better understand how SARS-CoV-2 affects white blood cells. Participants provide blood and other samples as well as access to their COVID-19 medical records as part of the study. The study to evaluate COVID-19 rebound included six participants (three men and three women with a median age of 42 years) who took Paxlovid within four days of initial symptom onset and then experienced recurrent symptoms; two participants (a 54-year-old man and 35-year-old woman) who experienced recurrent symptoms who did not take Paxlovid; and a control group of six people who had COVID-19 but did not experience symptom rebound. All participants were previously vaccinated and boosted against COVID-19, and none developed severe disease requiring hospitalization during acute infection or rebound. Investigators collected data on each participant’s clinical course and performed laboratory tests on blood and nasal swab samples.

Investigators found no evidence of genetic mutations that would suggest participants who experienced COVID-19 rebound were infected with a strain of SARS-CoV-2 that was resistant to Paxlovid. They also found no evidence of delayed development of antibodies in participants experiencing rebound after taking Paxlovid. Investigators detected robust SARS-CoV-2 T-cell responses in rebound patients. Overall, the level of T-cell responses was greater in rebound patients than in patients with early acute COVID-19 who did not experience rebound. Infectious SARS-CoV-2 was detected by viral culture in one out of eight rebound participants.

The findings suggest that rebound symptoms could be partially driven by the robust cellular immune response to residual viral RNA throughout the respiratory tract, rather than an impaired immune response allowing viral replication, according to the authors. Larger, more detailed epidemiologic studies are needed to further understand the clinical importance and epidemiologic consequences of COVID-19 rebound, the authors write. The authors note that the current data support the need for isolation in symptomatic rebound persons and the need to evaluate, in a clinical trial, longer courses of Paxlovid in immunocompromised individuals where the immune response may be ineffective.

NHSBT researchers discover new blood group system

A team of investigators from NHS Blood and Transplant (NHSBT) and the University of Bristol have discovered a new rare blood group system, called Er, after investigating three known antigens that did not fit into any known blood group system. The findings, published last week in Blood, also solved two 30-year-old cases of hemolytic disease of the fetus and newborn (HDFN).

In this study, researchers from NHSBT’s International Blood Group Reference Laboratory (IBGRL) investigated individuals with alloantibodies against a collection of antigens (Era, Erb and Er3) that were first observed more than 30 years ago using a technique that allowed for simultaneous analysis of gene coding DNA sequences. They identified specific changes in the gene coding for the PIEZO1 protein, which resulted in production of an altered protein on the cell surface of these individuals.

Using gene editing in an immortalized cell-line developed in Bristol, investigators removed and reintroduced the PIEZO1 protein to prove that alloantibodies to Er antigens (including two novel high-incidence antigens: Er4 and Er5) bind to PIEZO1. They also confirmed that PIEZO1 is required for Er antigen expression.

Investigators noted that while the newly discovered variations within the blood group system, Er4 and Er5, are extremely rare, they have been implicated in cases of HDFN. Two patients whose history was studied lost their babies due to HDFN.

AABB invites blood and biotherapies community to November virtual meeting

Registration is open for the upcoming AABB virtual meeting, to be held Nov. 6-7. Following the recent cancelation of the 2022 AABB Annual Meeting in Orlando due to Hurricane Ian, AABB is in the process of expanding this year’s previously planned virtual meeting to provide more content for attendees.

This year’s virtual meeting comprises an exciting and robust experience featuring both interactive “live” and on-demand sessions on critical topics in the blood and biotherapies field, many of which offer continuing education credit. The virtual meeting will feature critical education sessions, top scientific research, a keynote speech from Simon T. Bailey and more. More than 300 posters will be available in the virtual poster hall and many of the field’s top speakers will be presenting virtually. Attendees will have access to all sessions in an on-demand format, as well as the virtual poster hall, through Dec. 7. 

Additional information about the virtual meeting and a link to register is available on the AABB website. 

Prenatal steroid treatment may improve survival, reduce complications for extremely preterm infants

Steroid treatment before birth appears to improve survival and reduce complications among extremely preterm infants, according to a study funded by the National Institutes of Health. Antenatal steroid therapy, given to women at risk of preterm delivery, causes the fetal lungs to mature and has been shown to improve survival and reduce complications among infants born from 24 to 34 weeks of pregnancy. Previous treatment studies for infants born between the 22nd and 23rd week — those at greatest risk for death and disability — were inconclusive. 

The study was conducted by Sanjay Chawla, M.D., at Central Michigan University, Mount Pleasant, and Wayne State University, Detroit, and colleagues at 17 U.S. research institutions. It appears in JAMA Network Open. 

Of the mothers of the 431 infants in the study, 110 did not receive the steroid betamethasone, 80 received partial treatment (one dose) and 241 received complete treatment (two doses 24 hours apart). 

Of the infants exposed to complete treatment, 53.9% survived until discharge, compared to 37.5% with partial treatment and 35.5% with no treatment. Compared to infants receiving no treatment, infants exposed to full treatment were 1.95 times more likely to survive and 2.74 times more likely to survive without major complications such as severe bleeding in the brain, severe lung disease (bronchopulmonary dysplasia), cysts in brain, severe inflammation of the intestines (necrotizing enterocolitis) or abnormal blood vessel growth in the retina (retinopathy of prematurity needing treatment). 

The authors concluded that there is strong evidence to support giving antenatal steroid therapy to mothers at risk for delivery at 22 weeks. 

CMS continues to exercise pathologists and other laboratory staff enforcement discretion

During the Public Health Emergency (PHE), the Centers for Medicare and Medicaid Services extended enforcement discretion under CLIA to allow pathologists and other laboratory staff to review laboratory data, slides, and digital images in other locations, including their homes, without obtaining a CLIA certificate. 

CMS will continue to exercise this enforcement discretion under QSO-20-21-CLIA through the end of the current PHE. 

At the end of the current PHE, CMS will continue to exercise enforcement discretion for pathologists to examine digital images and laboratory data at remote locations.

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