COVID-19 Vaccination in Adults with Immune Thrombocytopenia (ITP): Data from the Platelet Disorder Support Association (PDSA) Patient Registry

BACKGROUND AND AIMS

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder causing low platelet counts (PC) and increased bleeding. COVID-19 vaccines are a major concern for ITP patients who fear vaccination might exacerbate their thrombocytopenia. To assess these concerns, PDSA developed a survey to explore how COVID-19 vaccinations impact individuals with ITP.

Methods

Data was collected using the ITP-COVID-19 web-based survey part of the Platelet Disorder Support Association's ITP Natural History Study. As of June 2021, 338 adult ITP patients had completed the survey. Data was analyzed with descriptive statistics and chi-squared tests.

Results

The majority of the 338 participants were female (78%) between 18-64 years of age (83%); 118 (35%) participants reported they were in remission, and 79 (24%) reported they had undergone splenectomy.

Viral Disease: Forty participants (12%) were diagnosed with COVID-19: 7 (18%) reported their PC increased from baseline, 20 (50%) reported their PC was unaffected, and 13 (32%) reported their PC decreased. Of the 20 participants who reported a PC change (increase or decrease) following a positive COVID-19 test, 13 (65%) reported their PC returned to baseline within four weeks following vaccination. Four patients (10%), all between the ages of 41-50 years, were hospitalized: 2 received dexamethasone, 1 received IVIG, and 1 required oxygen. Two of the 4 had been treated for ITP with corticosteroids within the last 6 months. Three out of 4 were female, and no additional autoimmune conditions were reported however, and 2 out of 4 reported co-morbid conditions including increased blood pressure, under-active thyroid, and allergies. No deaths occurred.

Vaccination impacts: 267 (79%) participants reported receiving at least one vaccine dose at survey completion, and 137 (41%) of participants reported they were fully vaccinated: Pfizer (45%), Moderna (38%), other (17%). Following at least one vaccine dose, platelet increases were reported by 37 (15%), 127 (53%) reported no change, and decreases were reported by 77 (32%); 26 did not answer. Of the 114 participants who reported a PC change following dose 1 (D1), 82 addressed the time for their PC to return to baseline; 69 (84%) reported their PC returned to baseline within four weeks.

Following dose two (D2), PC increases were reported by 18 (13%), 82 (60%) were unchanged, and 37 (27%) saw a decrease. Of 55 participants who reported a PC change following D2, 44 addressed the time for their PC to return to baseline with 31(71%) indicating their PC returned to their normal within four weeks. Changes in PC following receipt of D1 vs D2 were not statistically significantly (X ²=1.01, p=.31).

Following at least D1, three participants reported bleeding symptoms including epistaxis, wet purpura, petechiae, bruising, and a gastrointestinal internal bleed in an asplenic 64-year-old female with alpha-gal allergy. Twenty-four (9%) participants of 262 who answered the question, reported adverse effects other than bleeding including chills and fever. Two women, aged 35 and 47, developed a blood clot after receiving the Pfizer vaccine, despite reporting no past personal or family history of hypercoagulability.

Fourteen participants (13 females; 1 male) reported platelet decreases >100,000/µL following vaccination, but only one received rescue treatment. Two had a pre-existing autoimmune disorder and eight a previous splenectomy. Eight received the Pfizer vaccine, five Moderna, and one AstraZeneca.

Thirty (21%) participants reported a past change in platelets following a non-COVID vaccine; 23/30 shared their experience following receipt of D1 of a COVID-19 vaccine including 11 (48%) who experienced a platelet decrease, 4(17%) an increase, and 8 (35%) reporting no change.

Conclusion

The results are very reassuring for ITP patients that the risks of aggravated thrombocytopenia due specifically to getting COVID-19 infection or vaccine are small. There were only three cases of bleeding and two of clotting; all were well-treated. Decreases in PC following viral infection and vaccine receipt did occur, but they were rarely substantial and most resolved within four weeks. These very positive findings should reduce vaccine hesitancy among ITP patients and encourage them to be vaccinated.