Low clinical utility of testing for anti-platelet factor 4 in asymptomatic individuals after ChAdOx1 nCoV-19 vaccine.
Int J Lab Hematol
; 44(2): 424-429, 2022 Apr.
Article
in English
| MEDLINE | ID: covidwho-1541737
ABSTRACT
INTRODUCTION:
The development of anti-platelet factor 4 (PF4) antibodies is linked to a rare thrombotic complication described now as vaccine-induced immune thrombotic thrombocytopenia (VITT). This clinical syndrome with thrombosis and thrombocytopenia was reported after exposure to the Oxford-AstraZeneca COVID-19 vaccine, ChAdOx1 nCoV-19 vaccine (AZD1222), and Ad26.COV2.S vaccine (Janssen/Johnson & Johnson). In the absence of the clinical features, the incidence of positive anti-PF4 antibodies in asymptomatic individuals post-vaccination is unclear.METHODS:
The aim of this study was to evaluate the development of anti-PF4 antibodies in asymptomatic individuals 14-21 days after receiving the first dose of ChAdOx1 nCoV-19 vaccine (AZD1222) and BNT162b2 vaccine. Prospectively, we collected serum from individuals before and after ChAdOx1 nCoV-19 vaccine and BNT162b2 vaccine and measured anti-PF4 antibodies using the Asserachrom HPIA IgG ELISA (Stago, Asnieres, France).RESULTS:
We detected positive anti-PF4 antibodies in 5 of 94 asymptomatic individuals post-vaccine with a rate of 5.3% with low titers (OD 0.3-0.7). Four of 5 individuals who tested positive after the vaccine had also positive anti-PF4 antibodies before the vaccine, which indicates that a majority of the positive results are due to preexisting anti-PF4 antibodies. We did not find a relation between the development of anti-PF4 antibodies and the immune response to the vaccine, status of prior COVID-19 infection, and baseline characteristics of participants. None of the participants developed thrombosis nor thrombocytopenia.CONCLUSION:
Our results provide new evidence to guide the diagnostic algorithm of suspected cases of VITT. In the absence of thrombosis and thrombocytopenia, there is a low utility of testing for anti-PF4 antibodies.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Vaccines
/
COVID-19
Type of study:
Diagnostic study
/
Experimental Studies
/
Observational study
/
Prognostic study
Topics:
Vaccines
Limits:
Humans
Language:
English
Journal:
Int J Lab Hematol
Journal subject:
Hematology
Year:
2022
Document Type:
Article
Affiliation country:
Ijlh.13774
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