key: cord-0858209-jpa9sn2t
authors: Ulhaq, Zulvikar S.; Soraya, Gita V.; Indriana, Kristin; Devitasari, Rizky; Pradiptha, I. Putu Yupindra; Zulfikar, Dilloniar B.; Uxiana, Vita; Zulkarnain,; Rachma, Lailia N.; Arisanti, Ditya
title: The level of Ig anti‐RBD SARS‐CoV‐2 after two doses of CoronaVac vaccine
date: 2021-10-18
journal: J Med Virol
DOI: 10.1002/jmv.27390
sha: a7d96f7f73d842c757fb15cb5266e28c7bbe075a
doc_id: 858209
cord_uid: jpa9sn2t

nan

The level of Ig anti-RBD SARS-CoV-2 after two doses of CoronaVac vaccine Initially, a total of 131 subjects, consisting of 59 male (45%) and 72 female (55%) healthcare workers (mean age overall, 35.07 years old [range, 20-67]), were included (Table S1 ). Among them, 9.9% Table S1 ) initially had a negative Ig anti-RBD, but then converted to seropositive at Day 28 (Table S1 ). Among subjects with a positive Ig anti-RBD, twelve subjects had sufficient Ig anti-RBD levels based on the criteria published by the Food and Drug Administration for the emergency use of convalescent plasma for the COVID-19 treatment (cut-off ≥ 132 U/ml, range from 132.6 to 250 U/ml, subject number 2, 11-13, 17, 38, 61, 66, 102, 105, 100, and 118, see Table S1 ). Moreover, it is interesting to note that the antibody response was stronger in individuals previously diagnosed with COVID-19 (Table S1 ).

When the subjects were grouped based on the Ig anti-RBD measurement time at 7, 14, 21, and 28 days after the second vaccination dose, our data revealed that the level of Ig anti-RBD did not differ between groups (71.87 ± 24.69; 52.26 ± 7.35; 48.29 ± 13.17;

54.88 ± 6.44 U/ml, respectively, p = 0.736, Figure 1A (Table S1 ). Fourteen (48%) and 13 (45%) subjects had elevation and suppression of Ig anti-RBD level from baseline, respectively, while two subjects (7%) did not show any changes ( Figure 1B ). No significant difference was detected between the elevated and suppressed groups in terms of age and sex (p > 0.05) (data not shown). Similar to the first analysis ( Figure 1A ), no significant changes were observed between the level of Ig anti-RBD at Day 7 and 28 or 14 and 28 (89.85 ± 36.26 vs. 73.45 ± 11.15 U/ml, p = 0.575; 51.64 ± 7.25 vs. 48.03 ± 7.69 U/ml, p = 0.490, respectively, Figure 1C ). In addition, no statistically significant gender-based ( Figure 1D ) or age-based differences were observed neither on Day 14 nor 28 ( Figure 1E,F) Figure 1F ). of CoronaVac. We found that among five cases with a negative Ig anti-RBD after the second dose of vaccine, four were older than 40 years old (one case showed seroconversion after 2 weeks). Our data also indicated that subjects older or equal to 40 years old tend to have lower antibody responses towards the CoronaVac. This is in line with the overall notion that aging is associated with a slower and at times suppressed adaptive immune response and that the age-related decline in immunity tends to result in a reduction of a vaccine's prophylactic efficacy. 5, 6 The antibody titers of vaccinees with a pre-existing history of SARS-CoV-2 infection tend to be higher than those without a pre- Subbarao et al. 10 This is to be expected due to higher efficacy of mRNA vaccines, in general, relative to inactivated virus vaccines.

In addition to the above results, our additional data presented in Table 1 indicated that all patients with breakthrough infection had a similar level of Ig anti-RBD to the current report. However, it is interesting to note that all vaccinated subjects were either asymptomatic or exhibited milder symptoms, except Case number 7, and the symptoms were resolved within 7-14 days, similar to the previous finding. 11 The Ig anti-RBD levels in postinfected individuals were increased (Table 1 ), but this finding was not observed in Cases 2 and 8, in line with a previous report where patients with symptomatic infection did not respond or had lower antibody levels. 12 In Case number 6, the level of Ig anti-RBD was declined after 3 months and marginally closed to the threshold of positivity, and nearly 7 months later, the subject was reinfected with SARS-CoV-2 (Table 1) Thus, the potential of periodic booster vaccinations may be required. 13 However, further studies with a larger sample size are needed.

There are some limitations identified in our study. First, our data did 

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