COVID-19 Vaccination in Patients with Immune Thrombocytopenia
In this study, the authors investigated the effects of COVID-19 vaccination on ITP participants, primarily the effects on platelet count, bleeding, and ITP exacerbation. The study consisted of 200 healthy controls and 218 ITP participants, of whom were either in remission, had chronic ITP, persistent, newly diagnosed, or an unknown ITP duration. All healthy control participants received the Moderna vaccine while the ITP participants received one of three types: Moderna, Pfizer-BioNTech, or AstraZeneca.
There was a variability in how platelet counts changed after vaccination in both ITP and healthy participants. By the end of the 8-week study period, 63% of healthy controls and 55% of ITP participants experienced a decrease in platelet count. Some participants had an increased platelet count or no change in count When looking at all the study participants together, there was a small decrease in platelet count by the end of the study period compared to baseline. However, they identified that counts for both ITP participants and healthy controls responded similarly after vaccination.
The study highlighted some risk factors for a decreased platelet count following vaccination: (1) longer duration of ITP and (2) whether the participant was taking ITP medication at the time of vaccination. For participants actively taking ITP medication during the study, the majority were prescribed either glucocorticoids, eltrombopag (Promacta/Revolade®), or romiplostim (Nplate®).
Bleeding complications were experienced by five ITP participants, which occurred at varying times after vaccination, including blood in urine (hematuria), broken blood vessel in the eye (vitreous hemorrhage), nosebleed (epistaxis), oral mucosal bleeding, urinary tract (urogenital) bleeding, bleeding after vascular surgery, non-fatal brain bleed (intracranial hemorrhage), and a fatal esophageal bleed.
Thirty ITP participants experienced an exacerbation defined by: (1) a greater than 50% decline in platelet count (2) a count less than 30,000 microliters of blood with a greater than 20% decrease from baseline levels, or (3) the need for rescue therapy. Out of the 15 ITP participants who required rescue medication, they either experienced a complete response, partial response, no response, or had no recorded response. Overall, the authors say that participants who experienced ITP exacerbation responded well to therapy. The risk factors for exacerbation were: (1) having a baseline platelet count less than 50,000, (2) ongoing ITP treatment before receiving the vaccination, and (3) younger age.
Overall, this study highlights that COVID-19 vaccination is safe in ITP participants, but close monitoring of platelet counts is important.
Comments from PDSA’s Medical Advisors:
There are many studies now on the effect of COVID vaccines on ITP. The only differences in the studies are which patients with ITP are the ones whose platelet counts fell. Overall, these studies all seem to have similar findings as to platelet changes and bleeding effects in recipients with ITP. The percent of patients whose platelet count fell substantially to a low level was less than 10-20%. There was very little serious bleeding of any kind reported. Among the patients who experienced a platelet count fall, the likelihood that their count would remain very low long term was small. In summary, this is another study suggesting that there might be infrequent short-term platelet count changes in recipients with pre-existing ITP, but the clinical outcomes are virtually always benign.
Prednisone Plus IVIG Compared with Prednisone or IVIG For Immune Thrombocytopenia in Pregnancy: A National Retrospective Cohort Study
In this study, the following treatments were compared in treating pregnant ITP participants:  prednisone plus IVIG (combination group),  prednisone alone, and  IVIG alone. This collaborative study included 19 hematology centers in China. The baseline platelet counts for the prednisone + IVIG group was 13,000 prednisone alone group was 20,000, and the IVIG alone group was 16,000.
A “response” to therapy was classified into three categories:  ‘no response’, which was defined as a less than doubling of the platelet count compared to baseline OR a count lower than 30,000;  a ‘response’ was defined as having a platelet count between 30,000 to 100,000 OR a at least a doubling of platelet count compared to baseline; and lastly  ‘complete response’ was defined as a platelet count over 100,000. Over the duration of the study, platelets were measured every one to four weeks depending on the stability of the counts.
The authors saw no differences between any of the three therapy groups with regards to the mothers’ response to treatment. However, participants who received the prednisone + IVIG combination achieved a ‘response’ more rapidly (4.39 days) than those given prednisone alone (7.29 days). There was no significant difference in time to ‘response’ when comparing the combination treatment to the IVIG alone group (6.71 days). Additionally, the time that participants needed to take prednisone in the combination group (14 days) was shorter than those given prednisone alone (27 days).
Participants treated with the combined therapy received fewer platelet transfusions pre-delivery than the IVIG alone group and fewer participants received transfusions of any blood product in the peripartum period i.e., the period shortly before, during and immediately after birth. The difference in transfusion requirement between the combination and the prednisone alone group was not significant.
Lastly, the study found no significant differences among the treatment groups for neonatal platelet counts, incidence of stillbirths, preterm births, babies small for age, or Apgar scores (a measure of baby health 1 minute and 5 minutes after birth).
Comments from PDSA’s Medical Advisors:
Comments from PDSA’s Medical Advisors: Overall, this study was the largest to compare the effectiveness of combination treatment in pregnancies with over 100 pregnant women with ITP in each group. The groups did not appear to be particularly different from each other. In conclusion, combination treatment demonstrated a shorter platelet count response time and a shorter duration of prednisone use. In addition, participants required less pre-delivery platelet transfusions and peripartum transfusions of any blood product in the combination group. What was not clear is how the decisions were made as to the choice of treatment since there was not the “expected” difference in the groups e.g., the platelet counts pre-treatment were not substantially or significantly lower than those in the other groups.